More than 50 Egyptian security forces have died during a clash with Islamist militants in the Western Desert.
The militants opened fire on the group – a mix of police and armed forces – during a raid on their hideout near the Bahariya oasis, south-west of Cairo, the Interior Ministry said.
Fifteen militants, who were reported to belong to an extremist group called Hasm, also died in the attack.
Egypt is currently battling an Islamist insurgency.
Hasm – described by Egyptian security forces as an armed wing of the Muslim Brotherhood, an accusation the group denies – are one of several groups which have launched attacks in recent years.
The security forces are understood to have gone into the desert following a tip-off about a possible hideout.
But, according to a security source, their convoy came under attack by militants using rocket-propelled grenades and explosive devices.
The source said the situation was made worse as the militants were more familiar with the area, while the commanding officer was unable to call for land and air reinforcements due to poor telecommunications in the desert.
In total, 53 members of the security service died, sources told the BBC.