The most important war crimes case since the Nuremberg trial began Tuesday as the U.N. tribunal against Slobodan Milosevic opened in The Hague.

At the opening of case number IT0254T, U.N. chief prosecutor Carla Del Ponte accused the former Yugoslav president of "medieval savagery and calculated cruelty" as Milosevic glanced around the courtroom calmly.

Milosevic, 60, is the first head of state indicted for war crimes while in office. He could be sentenced to life imprisonment if convicted of any of the 66 specific charges contained in three indictments, one each for the wars in Croatia, Bosnia and Kosovo. The trial is likely to take two years.

In her opening statement, Del Ponte said the case would be a powerful demonstration that "no one is above the law" or beyond the reach of justice.

Milosevic was expected to give a lengthy opening statement on Wednesday, arguing that the trial is inherently unfair, and that the tribunal is illegal and biased, his legal advisers said.

Milosevic, who studied law but never practiced, has refused to appoint defense lawyers and will speak for himself.

The Milosevic case is the culmination of years of investigation and case files compiled since the Yugoslav tribunal was set up by the United Nations in 1993 to try those responsible for the violent collapse of the Balkans.

Prosecutors charge Milosevic was behind a systematic plan to create a larger Serb state through the forced expulsion and murder of non-Serbs.

The most serious charge against Milosevic, who ruled Yugoslavia for 13 years, is for genocide for the murder of thousands of Muslims in Srebrenica, Bosnia, in 1995. The general in command of that operation, Radislav Krstic, was convicted last year of genocide and sentenced to 46 years imprisonment.

The trial's opening phase, which may last four months, will focus on murder charges of hundreds of Kosovo Albanians by Serbian security forces and the expulsion of some 800,000 people from their homes in 1998-99.

In a pretrial brief on Kosovo made available Monday, Del Ponte said the prosecution's evidence "will lead to an irrefutable inference that the natural and foreseeable consequences" of Milosevic's actions was "the murder of thousands of ethnic Albanians, sexual assaults of Kosovo Albanian civilians and the destruction of religious and cultural property."

Among the dozens of witnesses she intended to call is Kosovo Albanian leader Ibrahim Rugova and the former U.S. head of a Kosovo peacekeeping mission, William Walker. Many others were to appear as protected witnesses whose identities will not be disclosed in public or in the courtroom.

Starting with Kosovo, deputy prosecutor Geoffrey Nice told the tribunal, Milosevic had command responsibility for the action of Serb troops and must be found guilty if it can be shown that he failed to prevent crimes he knew were happening.

The prosecution screened television footage of Milosevic's rise to power, whipping up Serb nationalism and directing Serb anger against other groups. "Nobody will be allowed to beat you," he told angry Kosovo Serbs in 1987, in a speech that launched him on the national scene.

"Did he know what was happening? Of course he did," Nice said, pointing to reports that reached the president's office and the international news coverage of the war.

"Why did he not stop these things that were occurring?" Nice said. "He did not confront his victims. He had these crimes committed for him by others."

Del Ponte said Milosevic "pursued his ambition at the price of unspeakable suffering to those who opposed him." All his actions were "in the service of his quest for power," she said, as Milosevic scribbled notes.

Legal experts said the case would be complex, with the prosecution obliged to draw a direct link between Milosevic and the crimes committed by Serb forces against other ethnic groups in his disintegrating country.

Del Ponte said Milosevic was on trial for his individual actions. "No state or organization is on trial here today," she said, anticipating Milosevic's defense that the trial was directed against the Serb nation.

She said her task was to "allow the voice of the victims to be heard. Many of the victims cannot come to you because they did not survive."

After years of gathering testimony and months of trial preparation, Del Ponte said "today, as never before, we see international justice in action," and noted the paramount place the case would have in history.

"This trial will make history, and we would do well to approach our task in the light of history,'' Del Ponte said. She accused Milosevic of trying to "undermine the solemnity of these proceedings" by mocking the court.

Milosevic has refused to recognize the legitimacy of the court, berating it as an instrument of his enemies, whom he identified as the western NATO alliance. He claims his actions as Yugoslavia's leader were to defend his country against terrorism and preserve its unity.

The case is being intensely watched by politicians and by the judicial establishment as they look for ways to bring powerful statesmen and leaders, including people such as accused terrorist Usama bin Laden, to justice.

The Associated Press contributed to this report.