UN prosecutors opened their genocide case against Radovan Karadzic today - despite his continued boycott of the case - calling him the "undisputed leader" of Serbs responsible for atrocities throughout Bosnia's brutal four-year war.

Yugoslav war crimes tribunal judges ruled that the case could start despite Karadzic's refusal to attend for the second straight day. Karadzic, who is defending himself, claims he has not had enough time to prepare.

With the defendant's chair empty, prosecutor Alan Tieger said Karadzic, "harnessed the forces of nationalism, hatred and fear to pursue his vision of an ethnically segregated Bosnia."

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Dozens of war survivors crowded into the courtroom's public gallery and other rooms set aside for them at the tribunal to watch the trial unfold. As the case began they whispered to one another, but gradually fell silent as Tieger began his opening statement.

Presiding judge O-Gon Kwon said he regretted Karadzic's decision not to attend the hearing and will consider imposing a lawyer to represent him if he continues to boycott the proceedings.

Karadzic faces 11 charges — two genocide counts and nine other war crimes and crimes against humanity. He has refused to enter pleas, but insists he is innocent. If convicted, he faces a maximum sentence of life imprisonment.

Kwon said he had warned Karadzic he must accept the consequences of refusing to be at his trial. The three-judge panel will decide how to proceed next week after the prosecution finishes its opening statement.

Tieger said some of the evidence against Karadzic would come from the defendant himself, in the form of telephone intercepts and transcripts of his speeches to Bosnian Serb lawmakers during the war. Insiders, international observers and victims of Bosnian Serb crimes that were the bloody hallmark of the 1992-95 war will testify, he said.

He mentioned Biljana Plavsic as one of Karadzic's key collaborators. Earlier Tuesday, Plavsic — the only woman among the 161 people indicted by the International Criminal Court for the former Yugoslavia — was released from a Swedish prison after serving two-thirds of an 11-year sentence for war crimes.

Tieger quoted Karadzic as saying before the war that Serb forces would turn the Bosnian capital Sarajevo into "a black cauldron, where 300,000 Muslims will die." He said witnesses who survived the deadly 44-month siege of the city would describe living "in constant fear, day after day, for years, knowing that they or their loved ones were targets."

The prosecution will call other witnesses from Srebrenica, where Bosnian Serb forces murdered more than 7,000 Muslim men and boys in July 1995, he said. They were "victims who miraculously survived by feigning death" and mothers who "tried in vain to shield their boys from being taken to the killing fields."