A Swedish charity accused American troops Monday of storming through a hospital in central Afghanistan, breaking down doors and tying up staff in a search for militants. The U.S. military said it was investigating the allegation. The Swedish Committee for Afghanistan accused the U.S. Army's 10th Mountain Division of entering the hospital without permission to look for insurgents in Wardak province, southwest of Kabul, according to the charity's country director, Anders Fange. Fange said Monday that the troops' actions were a violation of the sanctity of medical facilities in combat zones. ''This is simply not acceptable,'' he said. The U.S. troops entered the hospital looking for Taliban insurgents late at night last Wednesday, Fange said. He said they kicked in doors, tied up four hospital employees and two family members of patients, and forced patients out of beds during their search. When they left two hours later, the unit ordered hospital staff to inform coalition forces if any wounded militants were admitted, and the military would decide if they could be treated, Fange said. Navy public affairs officer Lt. Cmdr. Christine Sidenstricker confirmed that the hospital was searched last week but had no other details. She said the military is looking into the incident. ''We are investigating and we take allegations like this seriously,'' she said. ''Complaints like this are rare.''