Egypt extended a state of emergency in parts of the Sinai Peninsula for three months, as a roadside bomb wounded 18 policemen Sunday in the insurgency-wracked region, security officials said.

The attack happened near El-Arish, the capital of North Sinai province where the army is battling Islamic State group loyalists, according to the officials, who said the policemen were on leave.

Health ministry official Tarek Khater said the wounded were in stable condition in a military hospital in the city.

Egyptian security forces have come under frequent attack in North Sinai since the military toppled Islamist president Mohamed Morsi in 2013.

Prime Minister Ibrahim Mahlab said late Saturday that the extension of the state of emergency for a third time was necessary because of the "dangerous security situation".

It was originally declared in parts of the peninsula in October following the death of 30 soldiers in an attack close to El-Arish.

The region is a stronghold of the jihadist group calling itself "Sinai Province", which in November pledged allegiance to the Islamic State organisation that has seized swathes of Iraq and Syria.

Hundreds of Egyptian police and soldiers have been killed in attacks. The military says it has killed more than 1,000 jihadists in the Sinai.