Gunmen in a car shot dead an Egyptian army brigadier general and wounded two soldiers in eastern Cairo on Friday, the military said.

The attack came hours ahead of planned Islamist protests that have prompted the police and military to boost their presence in the capital and other cities.

The identity of the assailants was not clear, but militants have killed scores of policemen and soldiers since the army overthrew Islamist president Mohamed Morsi in July last year.

The military said in a statement that the assailants were driving a vehicle without licence plates. Security officials had earlier said the officer was a colonel.

Several high-ranking police and military officers have been killed in attacks since Morsi's overthrow.

Morsi's ouster and detention led to a massive crackdown on his supporters that killed hundreds of people and saw thousands jailed.

Many of the militant attacks have taken place in the north of the Sinai Peninsula where militants have pledged allegiance to the Islamic State group that controls parts of Iraq and Syria.

The Ansar Beit al-Maqdis group has also carried out attacks in Cairo and the Nile Valley, including an attempted assassination of the interior minister last year with a car bomb.