People walk outside a mosque that was attacked in the northern city of Arish, Sinai Peninsula (EPA)

At least 235 people have been killed after suspected militants set off a bomb and opened fire at a mosque in Egypt's restive northern Sinai province.

The attack on Friday targeted supporters of the security forces attending prayers there, two eyewitnesses and a security source said.

Eyewitnesses at Al Rawdah mosque in Bir al-Abed, near Arish city, told local media ambulances rushed to take the wounded to nearby hospitals.

A total of 235 people had been confirmed dead, a health ministry spokesperson said, adding it is feared the toll will rise.

Egypt has been fighting a vicious Isis insurgency in Sinai for the last three years. Friday's attack comes after a spate of recent bombings targeting the police and army.

While most militant attacks target the security forces, hundreds of civilians have been killed in the violence. Attacks outside the region have targeted Egypt's Christian minority.