No group immediately claimed responsibility for the attack but Islamist militants bent on toppling the Cairo government have in the past killed hundreds of police and soldiers, usually at checkpoints and barracks or police stations.

Attacks have increased since then army chief General Abdel Fattah al-Sisi led the overthrow of Islamist President Mohammad Mursi after mass protests in 2013 against his troubled year in office.

A shift towards attacks on softer tourist and economic targets could undermine Egypt’s efforts to win back foreign tourists scared away by political and economic turmoil since a 2011 uprising which ousted veteran autocrat Hosni Mubarak.

Tourism is one of the top sources of income and foreign currency earnings for the Arab world’s most populous country.

The security sources said Wednesday’s incident happened about 30 meters (yards) from a security checkpoint leading to the tourist site on the western outskirts of Cairo.

State news agency MENA confirmed that the policemen had been killed in the Haram area of Giza province.