A U.N. judge's injury delayed Monday's testimony from a former commander of U.N. peacekeepers in Rwanda whose superiors ignored his warnings of an impending slaughter in 1994.

Gen. Romeo Dallaire commanded the U.N. Assistance Mission in Rwanda, which remained in the tiny central African nation throughout the Hutu-organized genocide of more than 500,000 Tutsis.The 51-year-old Canadian was scheduled to take the stand Monday in response to a summons from attorneys representing Jean-Paul Akayesu, a former small-town mayor who is accused of genocide and crimes against humanity in the deaths of more than 2,000 Tutsis.

The lawyers say Dallaire's testimony "would be of capital importance to his case," but so far it is not clear why.

Akayesu's trial was delayed until Tuesday, or possibly Wednesday, because Judge Lennart Aspergen of Sweden fell off a horse Sunday and was recovering from minor injuries, said Judge Laity Kama of Senegal, president of the International Criminal Tribunal for Rwanda.

Akayesu, 44, former mayor of the central Rwandan town of Taba, has pleaded not guilty to 12 charges of genocide, crimes against humanity, murder and torture during the 100-day slaughter.

Months before the slaughter began on April 6, 1994, Dallaire warned the United Nations that radical Hutus were planning to massacre Tutsis. He sought to raid a Hutu militia arms cache, but was overruled by U.N. chiefs, including Annan, who then was head of U.N. peacekeeping operations.

In a message to his superiors dated Jan. 11, 1994, Dallaire said an informant, a top-level member of the ruling party's militia, had been ordered to register all Tutsis in Kigali, Rwanda's capital.

"He suspects it is for their extermination," Dallaire wrote, according to the Belgian investigation.

In less than three months, Hutu troops, militias and civilians launched a genocidal campaign that killed more than 500,000 people, mainly Tutsis, and forced more than a million refugees to flee to surrounding nations.