A man wearing an Afghan police uniform shot and killed two British soldiers at a checkpoint in southern Afghanistan on Tuesday, international military officials said.

The assault appeared to the be the latest in a string of insider attacks that have threatened the partnership between international troops and the Afghan forces they are trying to train to take over responsibility for the country's security.

A statement from the NATO military coalition said only that the assailant was wearing a police uniform, leaving open the possibility that the attacker was a militant posing as a policeman.