LONDON, (Reuters) – An Afghan policeman, who the  Taliban said was one of its fighters, has killed five British  soldiers at a checkpoint in Afghanistan, raising the possibility  that the militants might have infiltrated the police force.
The gunman opened fire at a military compound in Helmand  province on Tuesday, a day after Afghan election officials  cancelled a run-off vote in disputed presidential elections and  gave President Hamid Karzai a second term in office.

British soldiers returned fire but the policeman escaped and  is still at large, a defence ministry spokeswoman said. An  investigation into the shooting is under way.

“It appears that they were targeted because they were  engaged in what our enemies fear most — they were mentoring and  training Afghan forces,” British Prime Minister Gordon Brown  told parliament.