A Swedish charity in Afghanistan says a military raid on one of its clinics that led to the deaths of three people almost certainly involved international troops.

Jorgen Holmstrom, country director of the Swedish Committee for Afghanistan, said Wednesday that two patients in its clinic in Wardak province and a boy were taken away and killed on the night of Feb. 17.

He says earlier indications that foreign troops were involved had been confirmed by the U.N.'s assistance mission in Afghanistan.

UNAMA said in a statement this week that Interior Ministry special forces and international forces had conducted the operation.

The spokesman for the U.S.-NATO mission in Afghanistan, Army Col. Mike Lawhorn, says an investigation into the incident has begun.