CAIRO - The judge in the trial of Hosni Mubarak on Wednesday summoned the top brass in Egypt's new ruling military council and his former vice president to testify in closed sessions on the ousted leader's role in putting down protests against his rule.

Both the defense and prosecution in the case against Mubarak and six of his top security chiefs sought the testimony of Field Marshal Mohammed Tantawi, who was Mubarak's defence minister and is now the military ruler.

Also summoned were the military chief of staff Sami Anan and Omar Suleiman, who Mubarak appointed as his vice president during the uprising and was his powerful intelligence chief for nearly two decades.

Many Egyptians believe that their testimony is key in determining whether Mubarak ordered the use of lethal force against the uprising. Mubarak himself has said in his statements that his top military and security chiefs attended meetings with him during the 18-day uprising. Nearly 850 protesters were killed in the early days of the protests that forced Mubarak to step down in February.

But the judge's order that the sessions, which will run Sunday through Thursday, be closed to the media and public ensures that key details of those meetings will remain secret.

Mubarak, his former Interior Minister Habib el-Adly and six other top security officials are charged with complicity in the killing of protesters, a charge that carries a potential death penalty...

The judge's decision came in a stormy session during which a prosecution witness was detained on suspicion of perjury -- but then quickly acquitted by the court.

The witness, Capt. Mohammed Abdel-Hakim was the latest in a string of police officers that the prosecution has called to testify, expecting they would confirm that orders were issued for security forces to use live ammunition against the anti-Mubarak crowds in the streets.

But Abdel-Hakim denied in the court Wednesday that any live ammunition was provided to riot police or that he knew of any orders to shoot at protesters.

Lawyers for families of slain protesters accused Abdel-Hakim, who was in charge of ammunition for a Cairo security regiment,of changing his earlier testimony to investigators -- that he issued hundreds of bullets to each member of his force during the protests. Prosecutors immediately charged Abdel-Hakim with perjury and the judge ordered him detained, but then several hours later it was announced that he had been acquitted and freed, with no explanation.

In a session Monday, lawyers said four other officers of similarly changing their earlier affidavits to investigators once they testified in court.

Several of the family lawyers accused security officials and other Mubarak supporters of pressuring the witnesses to deny the existence of any shoot-to-kill orders for police. But there has been so far been no court investigation into the suspicions or the reasons for the changes in testimony, raising complaints that the prosecution is not being aggressive or organized enough in its case.

Omar Haggag, one of the family lawyers, said the judge summoned Tantawi and the other top leadership figures to avoid dragging on with testimonies from junior officials.

"He clearly aims to end the controversy on whether Mubarak ordered the shooting or not...it aims to save more time and effort in determining this," Haggag said.

The public has widely anticipated the testimony of Tantawi, who was a longtime loyalist and close associate of Mubarak -- not only because they wanted to see him implicate Mubarak, but they also wanted to finally answer the question about how close the two still are, and whether Tantawi is ready to officially break with his former boss. Mubarak handed over power to Tantawi when he resigned on Feb. 11.

Many protesters have grown increasingly critical of the military rulers' management of the transition after Mubarak stepped down, first by prolonging their stay at the helm. But also many are increasingly vocal about Tantawi and the ruling military council's failure, and often reluctance, to cut ties with the Mubarak regime.

Tantawi is to testify on Sunday, followed by other members of the military council and Suleiman, who has already given an affidavit to the investigators. The judge also summoned the current interior minister and another interior minister who replaced el-Adly during the heat of the uprising.