In Pakistan, at least four police officers were killed when a suicide bomber rammed an explosive-laden vehicle into a building housing a police unit in the north west of the country on Wednesday. Police said the attack in the city of Peshawar has left at least 28 people wounded. The building was completely destroyed in the blast. The Taliban has claimed responsibility for the bombing. The militant group has carried out a string of attacks that it says are revenge for this month's killing of Osama Bin laden.