Egypt's prosecutor general referred 278 suspected militia members to military trial on Sunday on "terrorism" charges, a judicial official said.
The defendants are facing charges including joining militant groups, carrying out 12 "terrorist operations" including targeting and killing police officers and security personnel and providing financial and logistical support to militants.
Of the 278 people referred for trial, 141 are already in detention.
Egypt's civilian and military courts have held successive trials for defendants accused of "terrorism" since the country's first democratically elected civilian president was ousted in a military coup in 2013.
Military leader, now president, Abdul Fattah Al-Sisi has since put in place a number of laws which ban opposition groups – in particular the Muslim Brotherhood, from which his predecessor emanated.
Mass trials have been held for suspected "terrorists" where hundreds are sentenced in one day in cases which see them given no chance for defence. Human rights groups have regularly condemned Egypt's judiciary and claimed it is being used as a tool to quash dissent and jail opposition figures.
Last week, 555 people were referred to military trial over accusations of belonging to a branch of a Daesh-affiliate in the Sinai Peninsula.