Egypt's army chief called Wednesday for public rallies this week to give him a mandate to fight "terrorism and violence," as Mohamed Morsi's supporters continue to protest against his ouster.

"Next Friday, all honourable Egyptians must take to the street to give me a mandate and command to end terrorism and violence," General Abdel Fattah al-Sisi said in a speech broadcast live on state television.

The army chief, who led a coup against Morsi on July 3 after mass demonstrations demanding his ouster, said he had warned the Islamist president that he must either resign or hold a referendum.

Presidential aides "told me if there is any problem, there will be lots of violence because of armed groups, to scare me," Sisi said.

His speech, at a graduation ceremony for cadets, came hours after a bomb at a police station killed a conscript, according to the interior ministry.

Almost 200 people have been killed in clashes since the days leading up to Morsi's overthrow, with militants in Sinai also carrying out daily attacks on security forces.