Afghan policeman kills two NATO soldier in southern Afghan province of Helmand

An Afghan policeman shot dead two soldiers from the US-led NATO coalition, the latest incident of a gunman in uniform targeting foreign personnel.

According to an International Security Assistance Force (ISAF) release, the policeman opened fire as the soldiers, whose nationalities have not been released, prepared to eat lunch at a police base in the southern province of Helmand.

It said the victims of Thursday's attack were part of a mentoring team, one of many working to train up the Afghan police and army to take over security across the country in the next three to four years.

"The shooter was seriously injured during the exchange and is currently in a medical treatment facility," ISAF said in the release, adding that an investigation had been launched.

Yousuf Ahmadi, a Taliban spokesman, said in a website statement that the policeman was an undercover Taliban agent who joined the force to carry out the attack and that 13 people had been killed.