The judge in the trial of Hosni Mubarak has 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 sought the testimony of Field Marshal Mohammed Tantawi, who was Mubarak's defense minister and is now the military ruler. Also summoned were the military chief of staff and Omar Suleiman, Mubarak's vice president and intelligence chief.

Many Egyptians believe that their testimony is key in determining whether Mubarak ordered the use of lethal force against the uprising.

But the closed sessions, to start Sunday, will keep key details about the relations between these top figures secret.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

CAIRO (AP) _ A prosecution witness was detained on charges of perjury during his testimony at the trial of ousted President Hosni Mubarak in a dramatic move Wednesday after a series of earlier witnesses also came under suspicion of changing their stories.

In a deep embarrassment to the prosecution, lawyers say four previous witnesses, all officials in Egypt's powerful security apparatus, gave courtroom testimony that differed from their earlier affidavits to prosecutors. The witnesses denied or said they had no knowledge that orders were issued to shoot protesters during the 18-day uprising that toppled Mubarak.

Mubarak, along with six of his top security chiefs, are on trial on charges of complicity in the killings of protesters, and showing that orders to use live ammunition to put down the demonstrations is key to the case.

In court Wednesday, the latest witness, Capt. Mohammed Abdel-Hakim, who was in charge of ammunition for a Cairo security regiment, denied any live ammunition was provided to riot police.

Lawyers for families of slain protesters accused him 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.

The family lawyers praised the move, after earlier criticism that the prosecution was not acting strongly enough to discipline its witnesses and present its case. Some family lawyers have accused senior security officials and Mubarak supporters of pressuring the witnesses into changing their stories.

"The prosecution took a brave step in response to the lawyers of the families, who were very upset because of all the perjuries," said Gamal el-Shukheibi, a lawyer for the slain protesters families. "It is clear the witnesses are coming under pressure to change their testimonies."

Some of the family lawyers say they intend to ask for similar perjury charges against the earlier witnesses. The state prosecutor would have to decide whether to press charges.

Prosecutors claim that Mubarak and former Interior Minister Habib el-Adly, his highest ranking security chief, issued the orders allowing use of lethal force against the peaceful protesters, which left nearly 850 protesters killed. The uprising eventually forced Mubarak to step down on Feb. 11.

Heavy security troops were deployed Wednesday outside the courthouse to prevent the scuffles that have repeatedly broken out between families of the victims, security and Mubarak supporters since the trial began Aug. 3. There were minor tension outside the court on Wednesday, with very few Mubarak supporters attending.

The judge had decided last month to ban live television coverage of the trial, a decision that has frustrated hundreds of victims' families and ordinary Egyptians who want to follow the historic proceedings.