You could call it theatre of the absurd — and it played out Tuesday in The Hague.

It was the much anticipated joint appearance in court by two of the most powerful figures of the Bosnian War of the 1990s.

The man once known as "The Butcher of Bosnia," former military commander Ratko Mladic, appeared as a witness for the defense of former Bosnian Serb leader Radovan Karadzic at the War Crimes Tribunal in The Hague.

Mladic slammed the UN's war crimes tribunal and refused to testify as a witness for Karadzic.

"What we weren't expecting was his first explanation for why he was unable to speak in court," said the BBC's Anna Holligan, who was in the courtroom. "He stood in the witness box and he said that he couldn't testify because he'd forgotten his dentures and he said to the judges, 'I have no teeth, I cannot talk.'"

After initially refusing to testify until he could put in his dentures, he also cited ill health and an unwillingness to risk incriminating himself as reasons why he was would not answer questions. Mladic's lawyer, Branko Lukic, told judges that Mladic could not testify because he suffers from a stroke-induced condition and can't tell fact from fiction.

Mladic was asked if he had ever informed Karadzic that "prisoners'' in Srebrenica would be, or had been, executed, an apparent reference to the 1995 massacre of thousands of Muslim men and boys. And Karadzic asked if the two leaders had agreed to subject residents of the Bosnian capital, Sarajevo, to a campaign of terror by shelling or sniping. But there was no answer.

The proceedings were adjourned after the judge said he wouldn't force Mladic to answer questions, but turned down his request to read a seven-page document he'd prepared. Karadzic and Mladic are facing separate trials for crimes including genocide. Both insist they are innocent, but face maximum life sentences if convicted.