The man behind whistleblower website Wikileaks says he is not in a position to record an interview amid claims his life is in danger.

Julian Assange, the Australian-born founder of Wikileaks, is said to be under threat with reports that the site has hundreds of thousands of classified cables containing explosive revelations.

There was an international uproar in April when the website released classified US military video which officials had been refusing to make public for three years.

The leaked video showed a US helicopter crew mistaking a camera for a rocket-propelled grenade launcher before firing on a group of people in Iraq.

Mr Assange has also told his supporters he is planning to release a video of a US air strike in Afghanistan that killed many civilians.

The 2007 video of the US army helicopter shooting civilians has already led to a chain of events which reportedly has Mr Assange in hiding.

A hacker blew the whistle on the US army intelligence analyst Bradley Manning, who allegedly handed that video to Wikileaks.

Mr Manning is now reported to be in custody in Kuwait.

The hacker says Mr Manning bragged to him about having thousands of diplomatic cables that would embarrass US secretary of state Hillary Clinton and several thousand diplomats around the world.

It has since been reported that American officials are searching for Mr Assange to pressure him not to publish the cables.

But an unnamed source in the Obama administration has told Newsweek that the US government is not trying to convince Mr Assange not to release the cables, but it is trying to contact him.

The World Today has also received an email from Mr Assange which says: "Due to present circumstances, I am not able to easily conduct interviews".

In an email to supporters this week, Mr Assange denies Wikileaks has 260,000 classified US department cables.

But he confirms the website has a video of a US air strike on a village in western Afghanistan in May last year.

The Afghan government said at the time of the attack that 140 civilians died.

Life in danger

Daniel Ellsberg, who leaked Pentagon papers in the 1970s showing government deceit over the Vietnam War, says he believes Mr Assange has reason to keep his whereabouts secret.

"I think it's worth mentioning [that there is] a very new and ominous development in our country," he said.

"I think he would not be safe, even physically, entirely wherever he is.

"We have, after all, for the first time ever perhaps in any democratic country... a president who has announced that he feels he has the right to use special operations operatives against anyone abroad that he thinks is associated with terrorism."

Mr Ellsberg told a US TV network Mr Assange's life may be in danger.

"I was, in fact, the subject of a White House hit squad in November on May 3, 1972," he said.

"A dozen Cuban assets were brought up from Miami with orders, quoting their prosecutor 'to incapacitate Daniel Ellsberg totally' on the steps of the Capitol.

"It so happens when I was in a rally during the Vietnam war and I asked the prosecutor 'what does that mean - kill me?' He said the words were to incapacitate you totally, but you should understand these guys, meaning the CIA operatives, never use the word 'kill'."

Professor Amin Saikal, director of the centre for Arab and Islamic studies at the Australian National University, says the US government has strong motivations for keeping video of the strike under wraps.

"That NATO operation in western Afghanistan caused quite a number of civilian casualties which caused outrage among the Afghan leaders," he said.

"The issue was also raised very strongly in the Afghan parliament.

"I suppose that the American authorities would be very adverse at the release of the video at this point which could cause more problems in the relationship between Afghanistan and Washington."

As far fetched as Mr Ellsberg's claim sounds, the national president of Whistleblowers Australia, Peter Bennett, agrees Mr Assange's life may be at risk.

"There is a lot of money to be made from wars. There is a lot of people who will become very, very wealthy through the course of this Afghan war," he said.

"To stop anybody raising questions about its conduct would put those profits at risk and profit is a high motivation to stop somebody interfering with those profits.

"It is possible that there are vested interests - military, political and certainly economic, possibly even criminal - who would rather him not release that information.

"There is a serious chance that his wellbeing could be at risk. If I was in his shoes, I would be taking all necessary precautions to make sure that my whereabouts and my wellbeing were being protected."