Egypt's official news agency says three suspected militants have died when their car blew up south of Cairo.

MENA says the explosion took place early on Wednesday in the town of el-Saf in Giza province.

The report quotes unnamed security officials as saying the three suspects were carrying an explosive device in their car and likely detonated it by mistake. MENA gave no further details.

Egypt has battled an Islamic insurgency for the past three years that dramatically escalated after the military's ouster last July of Islamist President Mohammed Morsi and its subsequent crackdown on his Muslim Brotherhood supporters.

An al-Qaida-inspired group called Ansar Beit al-Maqdis has claimed responsibility for a series of explosions and suicide attacks over the past year.