Eleven Egyptian policemen were killed when a roadside bomb blast struck their armoured vehicle in the restive Sinai Peninsula on Tuesday, security officials said. Islamist militants have claimed a string of attacks that have killed scores of policemen and soldiers, mostly in **rth Sinai, since the army overthrew president Mohamed Morsi in July last year. Egypt's military has sought to quell the militants in a massive operation that has killed scores of extremists and netted some of their leaders. The main militant group, Ansar Beit al-Maqdis, has ack**wledged the loss of some of its leaders, but has continued to attack both the security forces and Bedouin suspected of collaborating with them.