An Egyptian police brigadier general has been killed after a bomb exploded under his car, in the fifth such targeted attack in Cairo within a week.

The blast in the upscale western suburb of October 6 on Wednesday killed Ahmed Zaki, a commander of Egypt's central security forces, which have spearheaded a crackdown on supporters of ousted Islamist president Mohamed Morsi.

The general was killed as he headed for work, security officials said, adding that two conscripts were wounded in the attack.

A little-known group, Ajnad Misr (Soldiers of Egypt), said in a statement on Facebook and Twitter that it had killed Zaki.

The group has claimed several attacks on police in Cairo, and had warned of further retaliation for the crackdown on Islamists who back Morsi, who was deposed last July.

Video footage posted on newspaper websites showed the front of the car destroyed. It was painted light green, not the usual dark blue of police vehicles.

Police officers are increasingly having their cars repainted to avoid being easily targeted.

Zaki was the third senior police officer to be killed in Cairo since the start of the year. Three other police officers have been killed in four more attacks over the past week.

Ibrahim Mahlab, Egypt's interim prime minister, and Mohamed Ibrahim, the interior minister, attended his funeral later on Wednesday.

In the Mediterranean city of Alexandria, meanwhile, a police lieutenant was killed in a gunfight with wanted "terrorist elements", security officials said.

They said one "terrorist" was killed and another wounded, adding that police retrieved an explosives-laden belt and two home-made bombs.

Morsi was toppled by his army chief, Abdel Fattah el-Sisi, who is now the frontrunner in a presidential election next month.

Source: AFP