CAIRO : An Egyptian police officer was killed on Friday evening when a bomb targeting a traffic police kiosk in Cairo exploded, security officials said, the latest of such attacks.Militants have stepped up their attacks against security forces since the army ousted Islamist president Mohamed Morsi in July and the military-installed authorities launched a deadly crackdown on his supporters. A policeman and a civilian were also wounded when assailants threw the bomb from a nearby bridge onto the kiosk, located on a main square of the Egyptian capital, the officials said.The attack comes a day after a little-known jihadist group, Ajnad Misr, has vowed new attacks against security forces in retaliation to their crackdown on Morsi supporters that, according to Amnesty International, has claimed 1,400 lives. But the deadliest attacks have been claimed by Sinai-based Ansar Beit al-Maqdis, a jihadist group inspired by Al-Qaeda.Official figures show that more than 500 people - mostly policemen and soldiers - have been killed in bombing and shooting assaults by militants since July. Most militant attacks have been in the restive Sinai Peninsula, but in recent months brazen attacks have also been launched farther afield in the Nile Delta and in the capital. On Tuesday, two bomb blasts wounded six people including at least two policemen in Cairo and on April 2, a police general was killed when three bombs exploded in front of Cairo University.More than 15,000 Islamists, mostly from Morsi’s Muslim Brotherhood, have also been jailed, while hundreds have been sentenced to death after what are often speedy trials. The authorities blame the Brotherhood for the attacks and have blacklisted it as a ‘terrorist organisation’.