CAIRO - Ex-interior minister Habib el-Adli pleaded not guilty as he and six of his top aides went on trial in a Cairo criminal court on charges of ordering the shooting of demonstrators during protests that toppled former president Hosni Mubarak last February. El-Adli and his six aides made a brief appearance in the courtroom on the outskirts of Cairo before the Chief Judge Adel Abdel Sallam Gomaa, who postponed the trial until May 21 to allow more time for defence lawyers and ordered a bigger courthouse for the high-profile trial. As a usual procedure at the maiden hearing session, the trial started with a representative of the Public Prosecution reading the charges. The suspects were asked if they were guilty. "I'm innocent of ordering the killing of protesters," said el-Adli from behind bars as dozens of policemen stood outside the dock, where el-Adli and his aides appeared. The former long-serving minister is accused of having ordered security forces to fire at demonstrators and is held responsible for the state of insecurity that prevailed in Egypt after police disappeared from the streets on January 28. According to an official toll, at least 846 people were killed and several thousands wounded during 18 days of massive nationwide protests. The chief judge then listened to lawyers for el-Adli and the other six police generals and those of victims, who all called for more time to get acquainted with details of the case and a bigger courtroom for the trial. Both requests were approved by the court. Outside the court in New Cairo City, a spat erupted between policemen, cordoning off the court and securing the area from the early hours of the day, and relatives of the victims who raised portraits of their killed sons supported by some lawyers, who were denied entry into the courtroom. The policemen were later ordered to leave the area as military personnel took over the whole process. "The police are still dealing with relatives of the martyrs as if they were the criminals. This is completely unacceptable," said one lawyer. Reda Mohamed, the mother of 19-year-old Ahmed Mohamed, who was shot dead on January 28, was very angry with the policemen. "I will never feel calm until el-Adli and the other gangsters get penalised," Mohamed said, wearing in black and having a photo of her son. Some other protesters who were injured during the anti-Mubarak revolt also appeared outside the court building with some of them showing their injuries to the dozens of cameras covering the trial. The removal of el-Adli from office was one of the chief demands of protesters when they launched the revolution against the Mubarak regime on January 25. "Death penalty for el-Adli" was chanted by irate protesters outside the court, where riot police and Army tanks were stationed. El-Adli's aides for state security, public security, central security as well as police chiefs in Cairo, October 6th and Giza also denied they had received orders to shoot protesters, saying the policemen turned to their guns in self-defence. The Supreme Council of the Armed Forces, which runs the country after Mubarak, promised that those responsible for abuses of power will be brought to justice, including Mubarak, who is under preventive detention.