Judges at the U.N. war crimes tribunal for the former Yugoslavia barred the chief prosecutor from giving opening remarks Friday at the landmark trial of Bosnian Serbs accused in the massacre of thousands of Muslims.

The angry dispute between the four-judge panel and prosecutor Carla del Ponte marred the start of the court's largest trial yet — and one of its most important: Seven senior military and police officers are accused in the murders of 8,000 Muslim men and boys in the Bosnian Muslim enclave of Srebrenica 11 years ago.

Five of the suspects face genocide charges in the July 1995 killings, Europe's worst civilian massacre since the Holocaust. The slaughter, which took place a single week, has become one of the signature atrocities of the bloody ethnic wars of the 1990s that led to the breakup of Yugoslavia.

Del Ponte spoke for just a minute when defense attorneys objected, saying her remarks should be part of formal opening statements slated for Aug. 21, when the trial resumes after a summer recess.

Judges agreed. A clearly angry Del Ponte was forced to sit down, saying she was "utterly stupefied" by the objections.

The U.N. prosecutor had begun her statement by describing a ceremony she attended earlier in the week to mark the massacre's anniversary. Tens of thousands of mourners gathered Tuesday in Srebrenica for the reburial of 505 newly identified bodies recovered from mass graves. The remains of thousands of Srebrenica victims are still missing.

"Over 500 victims, men and boys, aged between 15 and 78 at the time of their deaths, joined some 2,000 victims in the ground of the cemetery," Del Ponte said.

After defense attorneys accused her of making an emotive speech, Del Ponte said: "No emotion. Absolutely no emotion. Facts, my dear defense lawyers, facts."

The Hague-based court has staged only a handful of trials dealing with the Srebrenica atrocities, including the case against former Serb leader Slobodan Milosevic, which was aborted with his death in March.

The two men viewed as chief architects of the slaughter — former Bosnian Serb leader Radovan Karadzic and his military chief Gen. Ratko Mladic — are still on the run.

In an earlier case, tribunal judges made the landmark ruling that Bosnian Serb forces waged a campaign of genocide in Srebrenica.

Gen. Radislav Krstic, Mladic's deputy, is serving a 35-year prison term for aiding and abetting genocide, and Col. Vidoje Blagojevic is appealing his 18-year sentence for complicity in genocide.

The suspects in Friday's trial are Vujadin Popovic, Ljubisa Beara, Drago Nikolic, Ljubomir Borovcanin, Radivoje Miletic, Milan Vero and Vinko Pandurevic. They face allegations ranging from genocide to murder and persecution. All have pleaded not guilty, and face maximum life sentences if convicted.

In one of several massacres listed in the indictment, Bosnian Serb special forces summarily executed more than 1,000 men who had been captured and imprisoned in an agricultural warehouse in the village of Kravica.

"The soldiers used automatic weapons, hand grenades, and other weaponry to kill the Bosnian Muslims inside the warehouse," the indictment alleges. The victims' bodies were dumped in two mass graves on July 14 — 11 years to the day before the start of Friday's trial.