CAIRO (Reuters) - Egypt's ruling military council head testified in the trial of Hosni Mubarak on Saturday in a hearing that could decide the fate of the ex-president accused of responsibility for the deaths of hundreds of demonstrators earlier this year. Lawyers representing some of the 850 people killed in the uprising that overthrew Mubarak complained Field Marshal Mohamed Hussein Tantawi gave evidence earlier than usual and left the courthouse without allowing them to cross examine him. "The measures were unusual ... The session started very early," attorney Wael Zekri told reporters. "By the time the lawyers arrived, the testimony was over." There was no immediate comment on the charges. The hearing began at around 8.45 a.m. local time, ahead of the time expected by lawyers, and the courtroom doors were locked shut after Tantawi's arrival. One lawyer submitted a request to the court to have the tribunal panel replaced, which would effectively delay the trial until October 30 to allow a review of the request. "The court had not been neutral in hearing the witnesses, including today's session," said Mamdouh Ismail, one of the lawyers representing the victims' families. "Thus, the plaintiffs' lawyers had not been able to present their questions to the witnesses," added Ismail, who had endorsed the request. The ruling military council has been under pressure to deliver swift justice for those killed during the popular uprising which culminated in Mubarak stepping down on February 11. The former president, the ex-interior minister Habib al-Adli and a number of police officers are charged with conspiring to kill some of the protesters. Mubarak, the first Arab head of state to stand trial in person since unrest erupted across the Middle East this year, denies the charges. Judge Ahmed Refaat, citing national security considerations, had ordered Tantawi's testimony be heard behind closed doors and under a complete news blackout. Tantawi had been due to testify on September 11, but failed to attend the session citing a crisis triggered by demonstrators trying to storm the Israeli embassy in Cairo, a move that forced the Jewish state to withdraw its ambassador. Many Egyptians feared Tantawi would not testify. But the military council head, who had served for 20 years as Mubarak's defense minister, on Friday confirmed he was attending the hearing due to the special significance of the case. The state news agency MENA quoted Tantawi as saying while military officers do not appear except at military trials, he wanted to "assert the rule of law which must be the guiding approach for the Egyptian state after the January 25 revolution." Former intelligence chief Omar Suleiman, who was briefly vice president, and Interior Minister Mansour el-Essawy testified behind closed doors last week. Egypt's armed forces chief of staff, Sami Enan, Tantawi's deputy on the ruling military council, was scheduled to testify on Sunday, also behind closed doors. But the delay in the trial is likely to push the testimony until after it resumes.