Egyptian authorities have referred 48 suspected ISIS members to military trial over three deadly church bombings, the public prosecutor's office said in a statement on Sunday.
Of the 48 suspects, 31 are in custody and 17 still at large, it said.
ISIS claimed responsibility for the three suicide attacks that targeted the churches in December and April.
A December 11 attack in the heart of Cairo on the Saint Peter and Saint Paul church, adjacent to the headquarters of Coptic Pope Tawadros II, killed 29 people.
On April 9, 45 people were killed in twin church bombings claimed by IS as Christians gathered to celebrate Palm Sunday in the cities of Tanta and Alexandria.
ISIS has threatened to carry out more attacks against Egypt's Christians, who make up around 10 percent of its population of about 90 million.
The suspects allegedly set up ISIS cells in Cairo and in the southern province of Qena, the statement said.