Egypt Muslim brotherhood Mohamed Morsi
The military coup that ousted Egypt’s Islamist president Mohamed Morsi was followed by protests and violence Reuters

A senior Egyptian security official has been killed by a bomb planted under his car in Cairo.

Police Brig Gen Ahmed Zaki had just left home in Cairo's western 6th of October suburb to work when the explosive device went off.

The general was taken critically wounded to a local hospital but died, officials said.

He was the third general killed in 2014 and the fifth security official targeted by a deadly attack this week.

Militant groups have increased attacks against security forces following the coup that ousted Islamist president Mohamed Morsi last July.

As a commander in Egypt's central security forces, Zaki had been at the forefront of a government crackdown on supporters of Morsi's Muslim Brotherhood.

There was no immediate claim of responsibility for the attack.

Earlier this week, a jihadist group named Ajnad Misr (Egypt's Soldiers) claimed responsibility for another bombing that killed a policeman in Cairo and vowed to launch more attacks against security officials in retaliation for the crackdown on Islamists.

According to Amnesty International more than 1,400 people, mostly Morsi supporters, have been killed in the crackdown. Another 15,000 people, mostly Brotherhood followers, have been detained.

According to official figures, more than 450 policemen and soldiers have also been killed in bombings and shooting by Islamist militants since July.