At least four Afghans were killed as suicide attackers blew up on Monday a truck bomb and raided the offices of a US charity in the southern city of Kandahar.

At least four Afghans were killed as suicide attackers blew up on Monday a truck bomb and raided the offices of a US charity in the southern city of Kandahar.

One attacker detonated the vehicle outside the offices of US-based International Relief and Development (IRD), before two others entered the compound and fired on security forces, said police and government officials.

"Four bodies, all Afghan civilians, and five people including a Nepali guard have been admitted to our hospital with injuries," said Sardar, a hospital doctor in a nearby Mirwais hospital.

The Kandahar government said the attackers struck at 6am (0130 GMT) and that two gunmen remained holed up in a veterinary clinic inside the compound -- which also houses UN offices -- and were shooting at security forces.

"There were three suicide attackers. One exploded in front of the office. The two others entered the compound (wearing suicide vests). They are still alive, but the police are surrounding them," said police spokesman Ghorzang.

Taliban spokesman Yousuf Ahmadi said the insurgent group carried out a car bomb attack in Kandahar, the militia's former capital and the largest city in southern Afghanistan, but claimed to have targeted the UN refugee agency.