At least 25 people, mostly soldiers, have been killed in a bomb attack on military buildings in the capital of Egypt's North Sinai province.

The flagship government newspaper, al-Ahram, said its office in the town of el-Arish, which is situated opposite a military hotel and base that security sources said were the intended targets of the bombing, had been "completely destroyed".

Suspected militants also killed an army major and wounded six others at an army checkpoint in Rafah, near the Gaza border.

A police officer has been killed in a roadside bomb planted by suspected Islamist militants in Suez City.

An Egyptian Islamic State group affiliate has reportedly claimed responsibility for the deadly attacks. 

An Islamist insurgency based in Sinai has killed hundreds of security officers since former president Mohamed Mursi was removed from power following mass protests against his rule.             

Tensions have also been raised across Egypt this week by protests, some of them violent, marking the anniversary of the 2011 uprising that ousted veteran autocrat Hosni Mubarak.

Earlier today a group of women held a protest in Cairo against the death of activists Shaimaa Sabbagh and around 25 others allegedly killed by security forces at rallies commemorating the 2011 uprising.

Ms Sabbagh, 32, died on Saturday as riot police were breaking up a small, peaceful demonstration.

Friends said she had been shot, and images of her bleeding body rippled out across social media, sparking outrage and condemnation.