A suicide bomber, disguised as a policeman, has killed an American soldier and wounded six other people at a police headquarters in northern Afghanistan.

Afghan officials said on Monday that a man wearing a police uniform blew himself inside the building.

General Abdul Rahman Sayed Kheil, a provincial police chief, said the bomber entered the police station while Afghan officials were meeting US soldiers advising a police training programme.

He said the blast killed an American soldier and wounded two others. Four Afghan security officers were also wounded in the blast.

Zabiullah Mujahid, a Taliban spokesman, claimed responsibility for the blast in a phone call to the Associated Press, the news agency reported.

The attack which took place in Pul-e-Khumri, the provincial capital of Afghanistan's Baghlan region.

The US military said it was aware of an incident including some casualties but could provide no further details.