Whenever Red Star Belgrade meet their local city rivals Partizan, the atmosphere is rancid with hatred and aggression. Their rivalry is as fierce and embedded as any in world football. But on the afternoon of 22 March 1992, when Partizan visited Red Star's 60,000 all-seater 'Maracana' stadium for a routine league match, something strange happened. Before the game, as the fans began making their way to the stadium from across the city, there had been sporadic outbreaks of fighting and violence. Inside the stadium, once the game had started, the Red Star 'ultras', massed in the north stand, began taunting the supporters of Partizan, denouncing them as 'faggots, Turks, Muslims, blacks, communists'. There was nothing unusual about any of this and no doubt the hooligan gangs of both clubs were eager for more trouble after the game.

Then, abruptly, the chanting stopped. The crowd watched as a group of Serbian paramilitaries (the self-styled 'Tigers'), dressed in full uniform, took up positions in the north stand. There were about 20 of them and, one by one, they held aloft road signs: '20 miles to Vukovar'; '10 miles to Vukovar'; 'Welcome to Vukovar'. More road signs were brandished, each one bearing the name of a Croatian town that had fallen to the Serbian army. From high up in the stand, Arkan, the notorious commander-in-chief of the Tigers and director of the Red Star supporters' association, emerged to receive the delighted applause of supporters who were no longer fractious but united in hatred of a common enemy - the Croats. The match continued, but what took place had less to do with sport than with ardent nationalism and with what it meant to be a football supporter in a country at war.

As Serbia moves uneasily towards a kind of western-style democracy, the Belgrade derby of 22 March 1992 is remembered now as a celebration of Serbian hooligan power and of a time when Serbian hooligan gangs seized control of football and of the criminal underworld, as well as committing some of the worst atrocities during the wars of secession in former Yugoslavia. It was a time when the Serbs of Belgrade became, unequivocally, the most powerful football hooligans in history.

'Looking back today at that particular match, it is ironic that the result never mattered,' says Igor Todorovic, a Serbian football commentator and contributor to the fanzines Daj Gol (Goal), Mi Smo Grobari (We Are Partizan) and Kop. 'I was there that day and it was remarkable when the supporters of the two teams, who hate each other so passionately, cheered together in unison. They had never done so before and I don't think they have since. The game finished goalless, which was hardly surprising. The players could barely concentrate; most of the Red Star players were watching what Arkan was doing in his box, not what the opposition were doing in theirs. We were united by nationalism and hatred of the Croats. There was an amazing sense of power within the ground, as if football supporters were changing the world. And in a sense they were, even if the situation was never to be repeated, even during the Kosovo conflict.'

Today, the hooligans of Belgrade may not be as powerful as they were during the Balkan wars, but they remain among the most violent and racist in world football. I have been to games in Belgrade where the violence between supporters was worse than anything I have witnessed in England, or indeed anywhere outside the former Eastern bloc. The violence is not restricted to football: Partizan and Red Star have affiliated clubs in other sports, such as basketball and handball, which are infected by hooliganism. Sometimes rival fans unite to disrupt public events, as they did when they smashed up Serbia's one and only attempt at a gay pride festival in 2001.

On 29 May 2003, I attended the Serbian cup final between Red Star Belgrade and Sartid of Smederevo, a small industrial town 20 miles south of the capital. The game was played in Belgrade at the Partizan Stadium. This should have been as unthreatening as a match between, say, Manchester United and Brighton & Hove Albion, which meant that I was not expecting any trouble. I was naive. Inside the stadium as many as 7,000 hard-core ultras from Red Star's north stand were massed together, chanting in unison. Theirs were catchy little numbers: 'We hope you die like all those Italians at Heysel'; 'You're going to get your fucking head stamped on like a Kosovan'.

At the other end of the stadium, a group of about 400 bewildered Sartid fans banged their drums. The game was dull, but ended disastrously for Red Star when Sartid scored a golden goal to win the cup in extra time. Hundreds of riot police and others on horseback responded to the agitation of the Red Star supporters by moving quickly to prevent them invading the pitch. But several hundred ultras escaped to attack the Sartid supporters; meanwhile, others were outside destroying the team bus of their own defeated team. Soon I found myself surrounded by Red Star supporters, dressed in red and white, who were pouring petrol on to plastic seats and setting them alight. Many were carrying knives and iron bars. The sense of violence about to erupt was intense.

The ultras of Red Star - the Delije or heroes - are the most feared, organised and uncompromising of the Serbian hooligan gangs. One of the founders of the Delije is a thin, silver-haired maths teacher called Zoran Timic. To meet him is to meet the antithesis of the stereotypical beer-bloated, shaven-headed English hooligan. He is pensive, quietly spoken and slight. When we go to a bar he mocks my English taste for beer and orders himself an iced cappuccino. Yet it is his role at games to 'choreograph the crowd', which, as he told me when I visited him at the official offices of the Delije at the stadium, he does enthusiastically with the aid of a megaphone. That the Delije have their own official offices is, in relative British terms, a bit like Roman Abramovich opening an office at Stamford Bridge for the Chelsea Headhunters. But then Chelsea, unlike Red Star, do not pay a hard-core of fans to travel to games and arrange choreography. Nor do they provide the 'boardroom' table around which hooligans plot attacks on rivals at home and abroad - something to which the Red Star hooligans are happy to admit and discuss.

The mood at the offices is one of suspicion mixed with bravado. It lifts when I tell them that I am a third-generation Liverpool fan. The Delije ask to see my tattoos. I tell them they are on my heart, which disarms them temporarily. They ask me if I was at Heysel. I wasn't, but I can give them details of what happened, which satisfies their blood lust. There is among the young Delije leaders, drinking free lager from the club bar and smoking cigarettes, a certain respect for the English hooligan. 'English fans don't have offices because all they do is fight,' says Marco, one of the young leaders, who refuses to concede that he is a hooligan. 'We organise the best choreography in the world. We're not just hooligans; we are ready for anything. For example, we showed those English homosexuals from Leicester how to fight a few years ago. We met them in the Uefa Cup and ran them in Leicester and again when we met up with them later in the year in Germany. We think that in England you don't realise how tough the Serbs are. We respect the English as the founders of hooliganism, but where are you now? Other nations have overtaken you.'

Padja, another young Delije leader, explains how he is responsible for smashing up the Red Star players' cars whenever they perform badly. He carries a handgun under his jacket and boasts of how he recently destroyed the car of Red Star's captain, Nemanja Vidic, after he appeared in a fashion shoot with the captain of Partizan. 'If you now have Kosovan refugees in your country,' he says, turning to me, 'it's your own fucking fault because you didn't let us finish the job. Now, they're all taking your money and your state benefits.'

Apart from a brief spell when he fell out of favour with Arkan, Zoran Timic has been Red Star's choreographer and mentor to young hooligans for much of the past decade. Away from football and teaching, he works on a history of Red Star, which he researches from a small room in his flat in north Belgrade. 'Football was a base for people to rebel against communism in Yugoslavia,' he told me. 'Most Red Star supporters were already very nationalist. What we did at the end of the 1970s was to take the choreography from Italian football and the hooliganism from England and mix it together to create our own style of football anti-communism. Hooliganism became a way of showing that we were free; of resisting the communist regime.'

The old multinational Yugoslav league, with its nationalist rivalries that communism could never fully suppress, was consistently marred by hooliganism. At first, the state-controlled media were reluctant to report on the growing hooligan menace. But then, on 14 September 1978, the country's first full-scale football riot took place when a train carrying Partizan supporters to a game against Sarajevo was halted by police at Sid in Croatia. The Partizan fans responded by demolishing the train. The violence spread to the town itself and the fans fought running battles with the authorities for many hours.

'You have to realise that the establishment may have been communist and pro-Yugoslav,' explains Igor Todorovic, 'but football fans in the main were not. Partizan fans might hate Red Star but, at the end of the day, they are still Serbs. One of our most famous sayings here is that "Serbs united will never be defeated". We take that sentiment very seriously.'

Throughout the late 1970s and early 1980s, the football grounds of Yugoslavia became popular places for nationalist recruitment. In May 1980, when the Yugoslav head of state, Marshal Tito, died, leaving behind no obvious unifying successor, nationalists, both in Serbia and Croatia, understood how they could use football to further their own ends. Nationalist football violence escalated in tandem with the crumbling of central control. The 'Gravediggers' of Partizan rampaged to the sound of British punk bands; the Red Star ultras attacked rival fans using bayonets and iron bars. In Croatia, one hooligan leader kidnapped a supporter of Hajduk Split and raped him with a broom handle over a period of two days.

By the early 1990s, hardline nationalist and anti-government sentiment was so entrenched among supporters that battles with police before and after matches were weekly events. On 13 May 1990, Red Star travelled to Croatia to meet Dynamo Zagreb, in what would be the last game before the collapse of the old Yugoslav league and with it the state itself. In what have been described as the worst scenes of football hooliganism witnessed in Europe, thousands of Delije fought the Zagreb 'Bad Blue Boys' mob, as well as the local police. The game - a portent of the wars that followed - was abandoned after 10 minutes, but not before Zagreb's best player, Zvonimir Boban, who later joined AC Milan, kicked a policeman who was trying to prevent Croatian hooligans from attacking the Red Star end. After this, the fighting went on for more than an hour and the stadium was eventually set on fire.

Some time in 1990, Serbian leader Slobodan Milosevic became so concerned by the activities of Red Star's Delije that Jovica Stanisic, the former head of state security who is now on trial for war crimes at the Hague, enlisted Zelijko Raznatovic - Arkan - to help control and direct the violence of the hooligans. Arkan, a criminal and agitator who was eventually assassinated on 15 January 2000, understood that Red Star could be for him what Real Madrid were for Franco, or the Italy team, playing in black shirts, were to Mussolini - a force of power and influence in wider society.

Arkan took over effective control of the Delije, running everything from ticket sales to foreign travel and intimidation of match officials. He built himself a luxury mansion overlooking the ground, a post-communist exercise in shiny marble and smoked glass topped with satellite dishes. Within a year, he began to recruit and organise groups of nationalists - the notorious paramilitary Tigers - to fight the 'patriotic' war in Croatia and, later, in Kosovo. The wars in these territories were as much about business as they were about politics. By invading, looting and setting up monopolies in oil, alcohol and cigarette companies, Arkan and his employers grew wealthy while ordinary Serbs struggled. Arkan recruited extensively from the north bank of the Maracana. Hundreds of hard-core fans took pride in joining his disciplined, clean-shaven mobile killing squads. But not all Tigers were Delije; many were Partizan Gravediggers.

One Red Star supporter, Dejan Vukelic, whom I met in a coffee shop in central Belgrade, explained how he was in China 'living above a brothel and taking full advantage' when the Balkan war broke out. He returned home to fight in the Yugoslav army, only to find the demoralised communist force in disarray. It was while he was in the army that he heard about Arkan's training camp. 'I went straight to Arkan's people in Croatia,' he says. 'As a nationalist I thought it was my duty to be there. At first, I was impressed with the order and the sense of discipline. The training was good and the emphasis on cleansing the Croatians and Muslims from Serb territory was essential. But I didn't witness the atrocities that the Western media talk about. I didn't see much criminal behaviour...'

Many of Arkan's paramilitaries are now back in Belgrade and once more involved in sponsoring crime and violence, before, during and after matches. To these disaffected men and their younger, admiring brothers, football is war and war is football. Can they ever be stopped?

Zeljko Tomic, a member of Serbia's Parliament, is a 36-year-old committed fan of Partizan Belgrade and a voice of sanity in the disturbed world of Serbian football. 'The first thing we need to do is tackle the problem of corruption in our football,' he says. 'If we continue to sell off our best players in scams there will never be any money in our football and the game will remain at a low level. When Partizan sold Mateja Kezman to PSV Eindhoven, for example, we were supposed to be sent new floodlights by Philips, the owners of PSV, but theywent missing en route. That kind of deal where someone pocketed all the cash for himself - at the club's expense - is typically Serbian.

'The other main area we have to address is violence at sporting events, particularly football. Over the past season the hooligan issue has not improved, with vicious fighting between fans of Partizan and Red Star, and with these fans and the police. All matches in Serbia are affected in one way or another. We have to reverse the situation.' Can you succeed?

'I don't know,' he says,cautiously, 'but we must try. The government has recently introduced a law to combat hooliganism, and I backed it. We are starting to make some progress.'

The violence among Serbian football supporters is not as extreme as it was in March 1992 when the Tigers invaded the north stand of the Maracana to display their road signs, their trophies of war. But the violence remains, as does the pervading fear among supporters. Fortunately, Serbs have never supported their national team, Serbia and Montenegro, with anything approaching the fervour they reserve for their clubs. That may change soon, however, if Montenegro, as expected, finally ends its uneven union with Serbia following a referendum later this year. The hooligans may then gather behind a united, fully Serbian national team. If and when this happens, the world of football had better watch out.

Serbia have been drawn with Spain, Belgium, Bosnia-Herzegovina, Lithuania and San Marino in Group Seven of the European phase of qualification for the 2006 World Cup in Germany.

From a world of violence: new century, old trouble

Zimbabwe

9 July 2000 Thirteen people are trampled to death in rioting during a World Cup qualifier in Harare. Hooligans invade the pitch after South Africa take a two-goal lead. Fans stampede towards the exits as police fire tear gas into the crowd.

Brazil

December 2000 109 Brazilian fans are injured when a fence collapsed at the São Januario stadium, in Rio, during a game between Vasco da Gama and Sao Caetano. The fence collapses as fans try to escape rioting in the upper part of the stand. The match is halted after 23 minutes.

Iran

December 2000 Following an ill-tempered Tehran derby, between Pirouzi and Estegahl, violence spills on to the streets as fans destroy cars and buses. Three players from each side and 60 fans are arrested; more than 250 coaches are vandalised.

Holland

16 December 2000 It takes 400 riot police with dogs and helicopters to quell rioting in Den Bosch, about 60 miles south of Amsterdam. Hooligans set fire to parked cars and buildings, including a blood bank. Several rioters smash their own vehicles into police cars. One hooligan is shot dead by police.

Argentina

31 August 2003 There are 71 fans injured in riots at a game between Boca Juniors and Chacarita in Buenos Aires. The hooligans, known as barrabravas (which roughly translates as fierce gangs), are an integral part of Argentina's football culture, with links to club officials, political leaders and, it is widely believed, to the police. Knives and guns are the weapons of choice for hard-core hooligans.

South Africa

25 November 2000 Bottles and rocks hurled at players and fans force officials to abandon the final between South Africa and Nigeria in the African Women's championship, which Nigeria win 2-0. At least five people suffered minor injuries in the unrest as riot police fired tear gas into the crowd.