In April, the website released graphic, classified video footage of an American helicopter gunship firing on - and killing - Iraqis in a Baghdad street in 2007, apparently in cold blood. The de-encrypted video, which WikiLeaks released on its own sites, as well as on YouTube, caused an international uproar. The Baghdad video has been WikiLeaks' biggest coup to date, although an extraordinary number of unauthorised documents - more than 1 million - have found their way to the website. These include a previously secret 110-page draft report by the international investigators Kroll, revealing allegations of huge corruption in Kenya involving the family of former Kenyan leader Daniel arap Moi; the US government's classified manual of standard operating procedures for Camp Delta, at Guantanamo Bay, which revealed that it was policy to hide some prisoners from the International Committee of the Red Cross; the classified US intelligence report on how to marginalise WikiLeaks; the secret Church Of Scientology manuals; an internal report by the global oil trader Trafigura about dumping toxic waste in the Ivory Coast; a classified US profile of the former Icelandic ambassador to the United States in which the ambassador is praised for helping quell publicity about the CIA's activities involving rendition flights; and the emails leaked from the embattled Climatic Research Unit at East Anglia in Britain, last November, which triggered the so-called ''Climategate'' scandal. That is one leak that might have bemused conservatives convinced that WikiLeaks is run by ultra-lefties. In the blogosphere, meanwhile, conspiracy theories abound that WikiLeaks is a CIA cyber-ops plot. Two years ago, a Swiss Bank in Zurich, Julius Baer, succeeded in temporarily closing down the website with a US District Court injunction after WikiLeaks published documents detailing how the bankers hid their wealthy clients' funds in offshore trusts (the banned documents reappeared on WikiLeaks ''mirror'' sites in places such as Belgium and Britain). The Australian government, too, has made noises about going after WikiLeaks, after the Australian Communications and Media Authority's secret blacklist of banned websites (websites which may be blocked for all Australians if the Rudd government goes ahead with its proposed internet censorship regime), turned up on the website last year. The communications regulator further expanded the blacklist to include several pages on WikiLeaks, whose crime was publishing a leaked document containing Denmark's site of banned websites.

To say that the list of rattled people in high places around the world is growing because of Wikileaks is an understatement. The fact that the website has no headquarters, also means the conventional retaliatory measures - phones tapped, a raid by the authorities - are impossible. Intense interest in Julian Assange started well before the Baghdad video was released, and viewed 4.8 million times in the first week. The former teenage hacker from Melbourne, whose mystique as an internet subversive, a resourceful loner with no fixed address, travelling constantly between countries with laptop and backpack, constitutes what you might call Assange's romantic appeal. But then there is the flip side: a man who believes in extreme transparency, but evades and obfuscates when it comes to talking about himself in the rare interviews that he gives - which are hardly ever face to face. The secretiveness extends to those close to him. One woman who speaks to me on the condition of total anonymity, lived in the same share house in Melbourne as Assange, for a few months in early 2007, when WikiLeaks was in its incubation period. The house was the central hub, and it was inhabited by computer geeks. There were beds everywhere, she says. There was even a bed in the kitchen. This woman slept on a mattress in Assange's room, and says she would sometimes wake up in the middle of the night to find him still glued to his computer. He frequently forgets to eat or sleep, wrote mathematical formulas all over the walls and the doors, and used only red light bulbs in his room - on the basis that early man, if waking suddenly, would see only the gentle light of the campfire, and fall asleep again. He also went through a period of frustration that the human body has to be fed several times a day and experimented with eating just one meal every two days, in order to be more efficient. ''He was always extremely focused,'' she says.

WE MEET in early May, the day after Assange slips back into Melbourne, his home town. He arrived on a flight from Europe, via the United States. Or so I understand from the person acting as our go-between. The same contact provides a Melbourne address, and instructions: ''Don't call a cab, find one on the street; turn off your mobile phone before you catch the cab and preferably, remove the batteries.'' Sitting outside at the rear of the address, I suspect that at the last minute, Assange won't turn up - though not because of the cold. After all, it's well known that he has been spending a lot of time in Iceland lately, advising the Icelandic government on new laws to strengthen freedom of expression and protections for sources and whistleblowers. Last year, WikiLeaks released a confidential document showing that the major Icelandic bank, Kaupthing, had loaned billions of euros to its major shareholders shortly before the great, global financial meltdown (the website also released the legal threat sent to them by the bank's lawyers). Suddenly, he is here - a tall, thin, pale figure with that remarkable white hair, looking very tired, and wearing creased, student-style, dark clothes and boots, and backpack. As we shake hands, he inclines his head slightly in a courtly, old-world manner, at odds with his youthful, student-traveller looks. When I remark that there's a lot to ask him, he replies: ''That's all right - I'm not going to answer half of it.''

Is Assange his real name? Yes, he replies, then says it's the name in his passport. ''What's in a name?'' he then adds mysteriously, casting doubt on his first answer. (At the time of writing, his passport status was apparently back to normal after immigration officials at Melbourne Airport said that his passport was going to be cancelled on the grounds that it was too tatty). ''It has been in a couple of rivers,'' Assange allows, of the state of his passport. The first time, as he recalls, in December, 2006, when he was crossing a swollen river during heavy rain, in southern Tasmania, and was swept out to sea. He swam back in. ''My conclusion from that experience is that the universe doesn't give a damn about you, so it's a good thing you do.'' Why did he have his passport with him? He had everything he needed for three weeks of survival, he replies. He needed his passport for ID when he flew to Tasmania. Doesn't he have a driver's licence? ''No comment.'' How true is the image of him as the enigmatic founder of WikiLeaks, constantly on the move, with no real place to call home? Is this really how he lives his life?

''Do I live my life as an enigmatic man?'' No - is it true you're constantly on the move? ''Pretty much true.'' Does he have one base he'd call home? ''I have four bases where I would go if I was sick, which is how I think about where home is.''

He has spent the best part of the past six months in Iceland, he says. And the next six months? ''It depends on which area of the world I'm needed most. We're an international organisation. We deal with international problems,'' he replies. Assange mentions four bases, but names only two. The one in Iceland, another in Kenya, where he has spent a lot of time, on and off, for the past couple of years. The Kroll report, released on WikiLeaks, reportedly swung the Kenyan presidential election in 2007. When he's in the country, Assange lives in a compound in Nairobi with other foreigners, mainly members of non-governmental agencies such as Medecins Sans Frontieres. He originally went to Kenya in 2007 to give a lecture on WikiLeaks, when it was up and running. ''And ended up staying there,'' I suggest encouragingly. ''Mmmm.''

As a result of liking the place or … ''Well, it has got extraordinary opportunities for reforms. It had a revolution in the '70s. It has only been a democracy since 2004 … I was introduced to senior people in journalism, in human rights very quickly.'' He has travelled to Siberia. Is there a third base there? ''No comment. I wish. The bear steak is good.'' Why did he go to Georgia? ''How do you know about that?''

I read it somewhere, I reply. It was a rumour. ''Ah, a rumour,'' he says. But he did go there? ''It's better that I don't comment on that, because Georgia is not such a big place.'' Living permanently in a state of exile, means that a person might always have the sharp eye of the outsider, I suggest. ''The sense of perspective that interaction with multiple cultures gives you, I find to be extremely valuable, because it allows you to see the structure of a country with greater clarity, and gives you a sense of mental independence,'' replies Assange. ''You're not swept up in the trivialities of a nation. You can concentrate on the serious matters. Australia is a bit of a political wasteland. That's OK, as long as people recognise that. As long as people recognise that Australia is a suburb of a country called Anglo-Saxon.'' Could he ever live in one place again? A brief silence. ''I don't think so,'' he says finally.

When he isn't being deliberately obscure, and even when he is, Assange has the measured tones of an academic, sometimes sounding, once we're deep in conversation, as if he's giving a lecture. He talks with conviction, with sincerity, without bravado, and wears his ''fame'' lightly. ''I don't see myself as a computer guru,'' he remarks at one point. "I live a broad intellectual life. I'm good at a lot of things, except for spelling.'' It may be unfair to suggest that he likes the dramatic possibilities of his role. Then again, there's no doubting those dramatic possibilities. At one point, thinking about some of the material leaked on WikiLeaks, I ask him how he defines national security. ''We don't,'' he says crisply. ''We're not interested in that. We're interested in justice. We are a super-national organisation. So we're not interested in national security.''

How does he justify keeping his own life as private as possible, considering that he believes in extreme transparency? ''I don't justify it,'' he says, with just a hint of mischievousness. ''No one has sent us any official documents that were not published previously on me. Should they do so, and they meet our editorial criteria, we will publish them.'' IN 1997, a remarkable book was released about the exploits of an extraordinary group of young Melbourne hackers. It was written by Melbourne academic Suelette Dreyfus, with, says Assange, research assistance from him. In the book, Underground, all the hackers had monikers. Assange is said to be the character Mendax. In the book Mendax/Assange was an unusually intelligent child, who never knew his father. His mother, an artist and activist, left home, in Queensland, aged 17, after selling her paintings for enough money to buy a motorbike. In Sydney, she joined the counterculture community, and fell in love with a young man she met at an anti-Vietnam War demonstration - who fathered Mendax. Within a year of his birth, the relationship was over. When Mendax was two, his mother married a fellow artist and actor-director, and the trio travelled from town to town as an on-the-road theatre family. But soon after Mendax turned nine, the couple separated and divorced.

Mendax's mother then started a relationship with a man who Mendax considered to be ''a violent psychopath'', a man with five different identities, who'd fabricated his entire background, including the country of his birth. They eventually fled, and began a life on the run, eventually ending up on the outskirts of Melbourne. Assange will neither confirm nor deny that he's Mendax. But in an extraordinary slip recently, on SBS's Dateline program, whose reporter, Mark Davis tracked him down in Norway earlier this year (the program screened last Sunday), Assange said that this man ''seemed to be the son of Anne Hamilton-Byrne of the Anne Hamilton-Byrne cult in Australia, and we kept getting tracked down''. Byrne was the leader of a cult, The Family, discovered in the Dandenong Ranges in the early 1980s. There were 14 children in the cult, who were treated abominably, and taught that they were all Byrne's children. All of them had their hair dyed blonde (the police finally caught up with the cult in 1987). Assange won't discuss the link with Byrne. He says only: ''My mother was never in a cult. I was never in a cult.'' My question about his own white hair goes nowhere. However, Assange told me when we first talked (we have several conversations), that his hair went white at 15.

''I was very blond until 12-ish, until puberty. I built a cathode ray tube at 15, at school, and connected it backwards. The Geiger counter went 1000, 2000, 3000, 40,000. That was about the time. Also I had some head scans, because I had something like viral encephalitis. It was very mild. I just lost feeling in one cheek. Earlier on, at nine, I'd had head X-rays because I'd headbutted a giant earth ball.'' In yet another intriguing twist, when I ask Assange about a civil rights organisation he helped run in Melbourne, in the early 1990s, and which raised allegations about child neglect in the social welfare system - during Jeff Kennett's time as premier - he says he was particularly concerned with one case. With extreme reluctance, he eventually explains that he knew people whose children had been abused. He won't talk about this in more detail either. But at a different point in the conversation he says that in the mid-1990s, he got involved helping the Victorian police track down paedophiles. ''That was just consulting on a couple of things,'' he says. Mendax had lived in a dozen different places in different states, by the time he was 15. Assange mentions that he went to 36 different schools, including correspondence. ''How we know, is that I added them up for my sentencing hearing,'' says Assange. The story gets complicated. In 1989, computers at NASA, the US space agency, were attacked. The word ''WANK'' appeared in huge letters across the monitor (an acronym for Worms against Nuclear Killers). The culprits have never been found.

But in 1991, Assange, still a teenager, and a key member of a hacker group called the International Subversives, was arrested and charged with more than 30 computer hacking offences. He and others, it was alleged, had hacked the systems of the Australian National University, RMIT, Telecom, and had even monitored the Australian Federal Police investigation into their activities. He eventually pleaded guilty to 24 charges and was placed on a good behaviour bond, and ordered to pay $2100. In Underground, Mendax devises a program called Sycophant, allowing the International Subversives to infiltrate computers at the Pentagon, National Security Agency, Motorola and NASA, among other organisations. Mendax left home at 17, married his 16-year-old girlfriend, and a year later they had a son. Assange has a son at university. Mendax's wife left him just after his 20th birthday, leaving him devastated. Assange, like Mendax, suffered a breakdown and was briefly hospitalised after being charged by police. He does agree that he had a spell of depression after his relationship broke up. I use the word marriage.

''Are you going to write that I've been married?'' he asks. It was written about him, I reply - although it was Mendax who was married. ''That may not be true, so you shouldn't write it,'' says Assange. I ask whether the mother of his son, was his wife. ''Maybe. Maybe not,'' he says, adding, ''I won't speak about my adult personal life.'' Is he currently married? ''No comment.''

His sense of humour flashes when I ask how living rough in the hills and fields outside Melbourne, after he was charged by police with computer crimes, affected him - and the way he thought about life. ''I thought I should buy shares in the internet,'' he quips. Perhaps he did. Assange isn't paid a salary by WikiLeaks. He has investments, which he won't discuss. But during the 1990s he worked in computer security in Australia and overseas, devised software programs - in 1997 he co-invented ''Rubberhose deniable encryption'', which he describes as a cryptographic system made for human rights workers wanting to protect sensitive data in the field - and also became a central figure in the free software movement. The whole point of free software, he comments, is to ''liberate it in all senses …'' He adds, ''It' s part of the intellectual heritage of man. True intellectual heritage can't be bound up in intellectual property.'' Did being arrested, and later on finding himself in a courtroom, push him into a completely different reality that he had never thought about - and in a direction that eventually saw him start thinking along the lines of a website like WikiLeaks, that would take on the world?

''That [experience] showed me how the justice system and bureaucracy worked, and did not work; what its abilities were and what its limitations were,'' he replies. ''And justice wasn't something that came out of the justice system. Justice was something that you bring to the justice system. And if you're lucky, or skilled, and you're in a country that isn't too corrupt, you can do that.'' In another life, Assange might have been a mathematician. He spent four years studying maths, mostly at Melbourne University - with stints at the Australian National University in Canberra - but never graduated, disenchanted, he says, with how many of his fellow students were conducting research for the US defence system. ''There are key cases which are just really f---ing obnoxious,'' he says. According to Assange, the US Defence Advance Research Project Agency was funding research that involved optimising the efficiency of a military bulldozer called the Grizzly Plough, which was used in the Iraqi desert during Operation Desert Storm during the 1991 Gulf War. ''It has a problem in that it gets damaged [from] the sand rolling up in front. The application of this bulldozer is to move at 60 kilometres an hour, sweeping barbed wire and so on before it, and get the sand and put it in the trenches where the [Iraqi] troops are, and bury them all alive and then roll over the top. So that's what Melbourne University's applied maths department was doing - studying how to improve the efficiency of the Grizzly Plough. This is beyond the pale. ''The final nail in the coffin was that I went to the hundredth anniversary of physics at the ANU. There were some 1500 visitors there - four Nobel prize winners - and every goddamn one of them was carting around, on their backs, a backpack given to them by the Defence Science Technology Organisation. At least it was an Australian defence science organisation.''

Assange says he did a lot of soul searching before he finally quit his studies in 2007. He had already started working with other people on a model of WikiLeaks by early 2006. There were people at the physics conference, he goes on, who were career physicists, ''and there was just something about their attire, and the way they moved their bodies, and of course the bags on their backs didn't help much either. I couldn't respect them as men.'' His university experience didn't define his cynicism, though. Assange says that he's extremely cynical anyway. ''I painted every corner, floor, wall and ceiling in the 'room' I was in, black, until there was only one corner left. I mean intellectually,'' he adds. ''To me, it was the forced move [in chess], when you have to do something or you'll lose the game.'' So WikiLeaks was his forced move?

''That's the way it feels to me, yes.'' So who leaks to Wikileaks? Assange says that intelligence agencies will never confirm or deny that they ''post'' documents, even when some of those documents display the letterhead of the intelligence organisation involved. ''I love classification labels, because if it says Top Secret on the front, I think 'this is probably an interesting document,' and legitimate,'' he says. ''There's a glut of information of low quality in the world. So information that has been restricted and suppressed - it's interesting that people have [spent] economic effort to restrict and suppress it - so info which has extra restrictions on it, usually has an extra ability to induce reforms if it's released. ''Intelligence organisations nearly always put what section it's from, and the classification label. Sometimes they'll use code words in the classification. They'll even classify the classification.''

It's curious, surely, given the Pentagon's anger over the leaking of the Baghdad video, that Assange hasn't been asked to come into some office, somewhere, and have a chat. He returned to Australia via the US with no trouble, I point out. ''I believe that there's an understanding that we have a lot of support within these organisations, and interference with us runs the risk of being exposed internally, and would likely be exposed by us,'' he replies. It's also curious that he hasn't been approached to work for any of the security agencies for ''the greater good''. WikiLeaks is for the greater good, he says. THE individual who sent WikiLeaks the Baghdad video remains invisible. WikiLeaks released two versions of the video - a longer version, and a shorter one - which has also caused much controversy. Twenty minutes was said to be missing from the longer version. It was like that when they received the footage, says Assange, and they were very careful to make as few edits as possible to the 18-minute version they released.

''In particular the first 11 minutes is one continuous take. And then there's only cuts for time, and only about three cuts. The first 13 minutes is when all the action happens.'' Why did WikiLeaks put a copyright symbol on the footage they released? ''We didn't have time to sort out copyright - about how all that should be managed,'' he replies. ''We had some ideas, but we were quite concerned about people taking material and misrepresenting it.'' As the list of rattled people in high places gets longer, Assange and his team have become used to an increased level of interest from the authorities - and security services, leaked documents from some of those services notwithstanding.

There are other security concerns as well. Two human rights lawyers who had been helping WikiLeaks were shot dead in their car on a Nairobi street last year. Assange himself has written an online article about increased surveillance activities, ''most of which appears to be the results of US 'interests' ''. In an email he sent out to journalists earlier this year, Assange wrote: ''We have had to spread assets, encrypt everything and move telecommunications and people around the world to activate protective laws in different national jurisdictions.'' In 2008, Islamic militants threatened WikiLeaks after the website ''mirrored'' a video of Dutch parliamentarian Geert Wilders' controversial view of Islam in his 17-minute film, Fitna. A trailer of the film had been uploaded to several video-sharing sites, including YouTube, causing fury in Muslim nations. Pakistan's government ordered the nation's internet service provider to block YouTube's sites, which caused YouTube to be blocked in other countries as well. YouTube removed the trailer and access was restored. Another website that hosted the trailer also removed it, saying the lives of its staff had been put at risk. WikiLeaks then mirrored the video, and got so much traffic that the site had to be temporarily taken off line. ''We republished the material because it had been censored because of the threat of violence. Then we received threats of violence [via] emails,'' says Assange.

''We didn't believe them to be credible threats in the sense that we have good physical security in the sense of our internet infrastructure, secret locations and our personnel. That technology is geared at dealing with spy agencies. Islamic militants don't have the capacity to get past those defences.'' He adds that his team has also received threats from US military militants - ''I deliberately use that word'' - which they had not found credible either. ''I did not feel that it was possible for them to carry out the threats.'' WikiLeaks, he maintains, has released more classified documents than the rest of the world press combined. "That shows you the parlous state of the rest of the media. How is it that a team of five people [WikiLeaks is run by five full-time ''staffers'' and almost 1000 volunteers] has managed to release to the public more suppressed information, at that level, than the rest of the world press combined? It's disgraceful. ''They don't want to give [out] any information unless it's going to sell more newspapers. The result is the public record is denied primary sources.'' Loading

He would like to see all media develop their own forms of WikiLeaks. That would point his own website out of business, I point out. ''We have a proposal to [an American foundation] for a grant to do just that,'' he replies.