Armed men have killed an Egyptian military officer and a soldier in an attack on an army vehicle northeast of Cairo, security sources say, raising concerns that an insurgency is taking hold beyond the Sinai Peninsula.

Tuesday's attack, which also wounded an army officer and a soldier, took place in Sharkia province in the Nile Delta.

The assailants, who were in a vehicle, opened fire with automatic weapons, security officials said.

The number of attacks has risen since the army deposed President Mohamed Morsi of the Muslim Brotherhood on July 3, following mass protests against his rule.

Most of the attacks on the army have been limited to the relatively lawless Sinai, near Israel and the Gaza Strip, which is ruled by Hamas, an offshoot of the Muslim Brotherhood.

More than 100 members of the security forces have been killed in almost daily attacks in Sinai since Morsi was toppled, some involving rockets.

On August 31, rocket-propelled grenades were fired at a vessel passing through the Suez Canal.

Elsewhere in Egypt, police are hunting for a veteran member of a former armed group in the south of the country.

Assem Abdel Maged of the Gamaa Islamiya is among several dozen activists sought by the police in Minya province after their operation on Monday to restore control over the town of Delga.

French citizen killed

In another development, the French Foreign Ministry confirmed the death of a French citizen who was beaten to death by fellow detainees while in Egyptian police custody after he had been arrested for breaking a curfew.

After being presented to state prosecutors, who decided to release and deport him, the man had been put in detention at a police station pending deportation, the sources said.

"There was a fight between him and six other detainees when he wanted to turn the light on while they wanted it off to go to sleep. They attacked him and he had a brain haemorrhage and died," one security source said.

There were conflicting reports on when he died.

The security sources said he had been arrested at the weekend and died on Sunday, while Vincent Floreani, French Foreign Ministry deputy spokesman, said he was killed on Friday in police custody.

Egypt's new government has been trying to restore security and create a sense of normality to bring back foreign investors and tourists to a country gripped by political upheaval since a revolt toppled President Hosni Mubarak in 2011.