A key prosecution witness in Saddam Hussein's trial will testify at an unexpected session Sunday because the former intelligence official is seriously ill with cancer, officials said Thursday.

The witness, Wadah Ismael Al-Sheik, was a senior Iraqi intelligence officer at the time of the Dujail massacre in 1982 that Saddam and seven other co-defendants are charged with, two lawyers said. They spoke on condition of anonymity to avoid compromising the case or the heavy security surrounding it.

Saddam made a defiant initial court appearance Wednesday on the murder and torture charges, along with the seven former government and Baath Party (search) officials, and chief prosecutor Jaafar al-Mousawi, outlined the case against the men. The three-hour session then adjourned until Nov. 28.

But in a surprise, lawyers said Al-Sheik will testify Sunday at a U.S. detention center where he is being held near Baghdad's international airport because of his cancer. If he recovers, he could be a defendant in a later case regarding another alleged massacre carried out during Saddam's rule, the lawyers said.

The session would not involve reconvening the full trial, but rather would be a hearing to take a deposition from al-Sheik, the lawyers said.

President Jalal Talabani (search) said in an interview with the British Broadcasting Corp (search). the trial was a positive step for Iraq, but he insisted he would refuse to sign any death warrants that might arise from the judgment of Saddam and his associates.

The trial "means the beginning of the rule of the Iraqi people, and it means that all dictators who are committing crimes against their people will have the same fate," Talabani told the BBC.

He added that he did not think the trial would provoke the nation's Sunni Arabs, who form the backbone of Iraq's insurgency and some of whom still support Saddam. He said when people saw the crimes Saddam had committed, they would change their minds about him.

The prosecution of Saddam could be a lengthy process. The Dujail case is the first of up to a dozen that prosecutors plan to bring to trial against Saddam and his inner circle for atrocities during their 23-year rule.

At Wednesday's session, Saddam was combative from the very start.

When the chief judge asked him to identify himself for the record, Saddam quickly turned the question back on the little-known jurist: Who are you? More importantly, who are you to pass judgment on the man who still considers himself the ruler of Iraq?

Sitting inside a white pen with metal bars, Saddam appeared gaunt and frail and his salt-and-pepper beard was unkempt as he pleaded innocent to charges of murder, torture, forced expulsions and illegal detentions.

If convicted, the 68-year-old former dictator and the others could face the death penalty for their role in the 1982 killing of nearly 150 people from the mainly Shiite town of Dujail north of Baghdad after a failed attempt on Saddam's life.

Iraqis and much of the Arab world watched glitch-filled TV coverage of the proceedings intently.

"Since the fall of the regime, we have been waiting for this trial," said Aqeel al-Ubaidi, a resident of Dujail. "The trial won't bring back those who died, but at least it will help put out the fire and anger inside us."

In Baghdad, Shiite construction worker Salman Zaboun Shanan sat with his family at home in the Shiite neighborhood of Kazimiyah, having taken the day off from work to watch the trial.

When Saddam appeared on television, his wife spat in disgust.

But across the Tigris River in the mainly Sunni Arab district of Azamiyah, some were embittered by the trial of Saddam, whose regime was dominated by Sunni Arabs who have now lost their power. "Saddam is the lesser of evils," said engineer Sahab Awad Maaruf, comparing Saddam to the current Shiite-Kurdish led government.

The White House said President Bush did not watch, even as the administration hailed the trial as a key step in Iraq's transition to a functioning democracy.

During the hearing, al-Mousawi said Saddam was closely involved in planning retaliation after an assassination attempt against him as he drove through Dujail in July 1982. Al-Mousawi said the prosecution had videos of Saddam personally interrogating four Dujail residents soon after his motorcade was fired on.

Saddam countered that videotapes should not be admissible as evidence, insisting they can be altered and faked. The judge did not respond to his argument.