Slobodan Milosevic was smiling, Justice Richard May was scowling, the witness was fidgeting and the prosecutor was staring at his desk.

The former Yugoslavian dictator had been trying to discredit evidence given by Sabit Kadriu, a Kosovar human rights activist, and was preparing for his final assault.

He wanted to show that Kadriu had links to the Kosovo Liberation Army and that the Kosovo Liberation Army had links to Osama Bin Laden.

"This document," he said, pausing to wave a piece of paper above his water jug, "reveals the presence of the al-Qaeda network in Kosovo and Albania."

Kadriu, 41, tapped his foot nervously and spat out: "That's a figment of your imagination."

Milosevic beamed. "No, it's an FBI statement to Congress talking about al-Qaeda, that's what it is. It is dated 18 December. It shows that the mujahedin were active in Kosovo and that . . ."

May, the presiding judge from Britain, cut in. "Mr Milosevic, this is supposed to be a criminal trial and not some kind of general political occasion. You are meant to be cross-examining the witness, not making speeches."

Milosevic: "Dobro, dobro [all right]."

Both men have been through this before - several times a day, in fact, since the trial began on 12 February at the International Criminal Tribunal for the Former Yugoslavia in The Hague, where Milosevic is accused of genocide, crimes against humanity and war crimes.

Time and again, May orders Milosevic to stop developing political arguments. Time and again, Milosevic concurs with his customary "dobro, dobro", and then proceeds to develop a political argument. The 60-year-old ex-dictator is, after all, a communist apparatchik, and he applies those two Marxist-Leninist ideas that everything is political and that politics is a trial of strength.

He does not appear to hold out much hope of a not-guilty verdict at the end of what is expected to be a two-year hearing into massacres, deportations and persecutions in Croatia, Bosnia and Kosovo. In this, he may be right.

Yet the defendant is less concerned with the courtroom than with the "world opinion" that he evokes repeatedly. It is not clear whether he simply wants to sketch out his own political testament, or whether he hopes to emerge as a martyr of such heroic proportions that no country will accept him in its jails.

Whatever the truth, there is little doubt that he has so far outwitted a distinctly cumbersome prosecution team under the leadership of Carla Del Ponte from Switzerland. On the first day of the hearing, for instance, she accused him of orchestrating a decade of "medieval savagery" in the Balkans.

Her comment grabbed the headlines; but by focusing on the wider issue of Serbian atrocities, rather than on Milosevic's specific responsibility for them, she played straight into his hands.

"You are attacking a whole nation," he replied. "You are accusing all the Serbian people, inside and outside Serbia, who supported me and still support me to this day."

It was a bad start for the prosecution, and things have got worse since then. Milosevic, who is defending himself, is sharp, ruthless and domineering. He sits on the far side of a courtroom, shielded by bulletproof glass, perched on a blue swivel chair that gives him a clear view of prosecution witnesses for whom he shows not the slightest trace of compassion.

Agim Zeqiri, for instance, told of the murder of his wife and 15 of his relatives by Serbian forces at Celina, a small village in southern Kosovo, in March 1999. But faced with a gruelling cross-examination from Milosevic, he became confused, admitted that KLA gunmen had been present in the area on the day of the deaths, and finally pleaded with the judges to be allowed to leave.

Halit Barani, a Kosovar rights activist, then arrived in court with what he said was a Serb list of Kosovar Albanians "to eliminate". Milosevic took no time to spot the spelling mistakes in a document that he said could not have been written by a Serb-speaker, and which was therefore a forgery. Such victories, of which there have been many since 12 February, have boosted Milosevic's popularity in Serbia to such an extent that state television has stopped its daily half-hour broadcast from The Hague.

"This tribunal is allowing Milosevic to use his demagoguery and run the proceedings," said the Serbian prime minister, Zoran Djindjic. "It is a circus." Djindjic was exaggerating, but only a little.

For all his withering haughtiness, May is struggling to keep the most important international trial since Nuremberg within the boundaries of criminal law. The bench, for instance, is raised so that it can oversee proceedings, as in national jurisdictions. Yet such is the brute force of Milosevic's personality that other participants are often turned towards him, like pupils towards a teacher.

What they hear is a lesson in cunning cynicism. Milosevic claims, for instance, to be on his own, isolated from his family, his friends and his advisers by the international conspiracy against his country. In fact, he has two lawyers in The Hague, but they sit in the public gallery, out of view of the cameras that relay proceedings on the internet. He is at the centre of what can only be a powerful and wide-reaching support network.

One witness said he had been dismissed from his civil service job in Kosovo. Milosevic knew that he had, in fact, been given early retirement and was receiving a pension. Another said he had been fired as a train driver for speaking Albanian in 1990. Milosevic said he had been sacked after an accident three years earlier.

This information is coming from a unit set up in Belgrade by Milosevic's supporters, who appear to have unfettered access to Serbian secret service files. Milosevic telephones them several times a day as he prepares for prosecution witnesses. When he conducts his cross-examinations, he keeps his voice low, and drapes his arm over the chair beside him.

To date, just one prosecution witness has stood up the former Serbian strongman: Lord Ashdown. The Liberal Democrat peer came to tell the court of the ethnic cleansing he had witnessed in Kosovo in 1998, and of his subsequent meeting with Milosevic in Belgrade.

When the defendant tried to draw him into a broad debate over the Nato intervention in 1999, Kosovar terrorism and the supposed western conspiracy against Serbia, Lord Ashdown just laughed.

"I have heard some fantastic conspiracy theories from you, but this one exceeds all the others," he said. "The idea that this is some kind of hegemony by the west to run other countries is so far-fetched that I don't think even you believe it."

Milosevic, for once, was silenced.