In Afghanistan, at least three militants have been killed in an attack on a police training centre outside the southern city of Kandahar. There are also reports of police casualties in the battle. A number of men armed with rocket propelled grenades and automatic weapons stormed the centre. Tens of thousands of Afghan police and troops are being trained to assume full security control once Nato leaves. The Taliban say they carried out the attack. The gun battle inside the police training and recruitment centre lasted more than an hour. Witnesses heard a number of explosions. Reports say one or more suicide bombers could have been involved. The area was sealed off and helicopters were seen flying overhead. Kandahar has seen a number of insurgent attacks on police in recent months. In February, 19 people were killed in an assault on the city's police headquarters.