Two NATO soldiers serving with the International Security Force were gunned down Tuesday in the southern province of Helmand by an individual wearing an Afghan police uniform, ISAF said.

"An individual wearing an Afghan National Police uniform turned his weapon against ISAF forces in southern Afghanistan, killing two soldiers," the ISAF spokesman, Gen. Hagen Messer, said.

He added that ISAF has launched an investigation to determine exactly what happened.

NATO does not normally specify the nationality of soldiers who are slain, a responsibility that is left up to each member country, though the fact is that Helmand has a large presence of British and American troops.

So far this year, more than 50 foreign soldiers have been killed in attacks by members of Afghan security forces, sometimes Talibans who managed to infiltrate these armed units.

NATO has limited some of its training and cooperation programs with the Afghan army and police, and recently announced measures that attempt to reduce the risk of such activities.

International troops began in 2011 their progressive withdrawal from Afghanistan and a gradual transfer of security duties to local police and military. EFE