A State Security Court Sunday in the Upper Egyptian city of Qena postponed until April 18 the trial of three Muslims accused of killing six Copts and a Muslim policeman in the Upper Egyptian city of Naga Hammadi last month. "The trial will resume on April 18 to hear the prosecution witnesses," the Chief Judge Mahmoud Abdel Salam said Sunday. Tight security measures were taken as black-clad police guards surrounded the court building, while 15 trucks of troops were standing nearby before the defendants were brought to the court in the early morning. "We had support troops from the security departments in Assiut and Sohag to help us cordon the area during the court session," a security official who spoke on condition of anonymity, said. Egypt's Prosecutor General has charged the three with murder and threatening national security in the attack on Coptic Christmas Eve on January 6. Meanwhile, Nabih el-Wahsh, the lawyer for the main defendant, withdrew from the case on Saturday saying the court did not let him talk to his client. President Hosni Mubarak promised a quick trial for the suspects following nationwide protests by Egyptian Christians demanding better police protection.