Egypt's army spokesman, Mohamed Samir, said Friday night on his official Facebook page that military and police forces arrested in several governorates 18 Egyptians suspected of militant activity.
The suspects were arrested in North Sinai governorate, the Suez Canal governorate of Ismailia, and the Nile Delta governorate of Daqahliya.
A statement by Samir said the suspected militants are currently being questioned.
Egypt's police and army have come under frequent attack by militants after the bloody dispersal by police and armed forces of a sit-in supporting ousted president Mohamed Morsi in August 2013. Hundreds of police and army personnel have been killed since.
Last Saturday, gunmen killed 21 military border guards in western Egypt in one of the largest assaults targeting security forces in recent years.
Egypt's constitution allows for military trials of civilians involved in acts against its armed forces.