Saddam's trial on charges of crimes against humanity was "a direct threat to international law, the United Nations, universal human rights and world peace," Clark said at a news conference. He demanded that proceedings be transferred from the Iraqi Special Tribunal to a new court that could work independently, free of prejudice.

Clark, who was attorney general under President Lyndon Johnson from 1967-1969, said the United States wanted the trial to "vindicate its invasion, to validate its occupation, and to make the world believe that the Iraqi people demanded that Saddam Hussein and leaders in his government be executed."

Clark has become known for his radical left-wing politics and for defending controversial figures, including ousted Liberian leader Charles Taylor, former Yugoslav president Slobodan Milosevic, who died in April, and Elizaphan Ntakirutimana, a leader in the Rwandan genocide.

Saddam's trial has been rocked by the murders of two defense lawyers and one judge. It is currently adjourned until May 15 but Clark said the defense would seek at least another month to review documents.

So far in the trial, he said Saddam's defense lawyers have been denied exculpatory documents and evidence, as well as witnesses statements and court transcripts.

The judges have either been Kurds or Shi'ites, and the defendants with one or two exceptions Sunnis, he said. "It's a sectarian persecution, if you will."

Clark said a fair trial in the midst of such widespread violence sweeping the country was impossible.

He said it should be transferred to a court that was legal, independent, impartial and competent, working in a safe environment "free of prejudicial influences."

Saddam and seven others are on trial for the executions of 148 people in Dujail in 1982 following a failed assassination attempt. Clark said those executed had signed confessions and under Iraqi law, the death penalty was mandatory for treason.

"It is common for the law to require the highest official of a state to approve and sign death warrants. George W. Bush signed 152 such warrants as governor of Texas," he said.