BAGHDAD, Iraq — Saddam Hussein insisted again today that he had been beaten by his American captors, denouncing Washington's denials as "lies" and mocking President Bush's claim that Baghdad had chemical weapons.

In courtroom turmoil, an assistant prosecutor asked to resign and the defense team threatened to leave court unless a guard was removed. The judge ordered the guard out. He also admonished Saddam's half brother, once head of Iraqi intelligence, to speed up his answers.

When the court gave the former leader an opportunity to cross-examine witnesses, Saddam instead used the time to expand on earlier assertions that he had been abused in custody. He claimed that the wounds he suffered from the alleged beatings had been documented by at least two American teams.

U.S. officials strongly denied the allegations.

Today, Saddam said American denials couldn't be believed, noting that no weapons of mass destruction had been found in Iraq despite Bush's pre-war claims that Saddam was harboring such weapons.

The former Iraqi leader and seven co-defendants are on trial for the deaths of more than 140 Shiites after a 1982 attempt on Saddam's life in the town of Dujail, north of Baghdad.

The first witness today — speaking from behind a curtain and with his voice disguised — said he was 8 years old at the time of the killings in Dujail. He said his grandmother, father and uncles had been arrested and tortured, and that he'd never again seen his male relatives, implying they'd been killed.

Saddam said the court should not depend on the testimony of witnesses who had not reached adulthood at the time of the alleged crime. The witness then told a defense attorney he hadn't been arrested and didn't see any dead bodies.