Egypt's interior ministry announced that a police brigadier-general was killed when two roadside bombs targeting riot police detonated outside Cairo University's faculty of engineering. At least five officers were injured in Wednesday's twin blasts, the ministry added.

Officials said the bombs, hidden in bushes, occurred within short succession of each other. Their target is thought to be riot police, who are deployed daily to the area in expectation of protests by supporters of ousted Islamist President Mohammed Morsi.

There was no immediate claim of responsibility for the attack.

Shootings and bombings directed at security officials has become frequent since the army ousted the democratically elected president Morsi last July.

Egypt's government announced this week that the death toll from such attacks is nearing 500. Most of those killed were soldiers and police. Hundreds of Morsi supporters were sentenced to death last week for their alleged roles in the violence.

Analysts expect violence to escalate in the lead up to the May 26-27 presidential election.

Former army chief and minister of defense Abdel Fattah el-Sissi, the general who toppled Morsi, is expected to easily win the vote.

jlw/se (Reuters, AFP, AP, dpa)