KABUL, Afghanistan (AP):

Seven American troops and four Afghans died in a Black Hawk helicopter crash yesterday in southern Afghanistan, the NATO military coalition said. The Taliban claimed their fighters shot down the aircraft.

The crash marked another deadly day for the United Stated (US) in Afghanistan, less than a week after six American service members were gunned down, apparently by two members of the Afghan security forces they were training to take over the fight against the insurgency as international combat troops prepare to exit the country by the end of 2014.

The spike in American deaths and attacks by Afghan allies have stirred fresh doubts about the prospects for the US plan to leave a capable Afghan government in place when most troops depart after more than a decade of war.

Initial reports

Spokesman Brig. Gen Gunter Katz said the NATO coalition is investigating the cause of Thursday's crash in Kandahar province, though US officials said initial reports indicated it had not been shot down.

Kandahar is a traditional Taliban stronghold and the spiritual birthplace of the hardline Islamist movement that ruled Afghanistan before being ousted in 2001 by the US-led alliance for sheltering al-Qaida's terrorist leaders.

No survivors

Among the dead were seven American service members, three members of Afghan security forces, and one Afghan civilian interpreter, said Jamie Graybeal, a spokesman for the coalition. He said there were no survivors of the crash. He declined to give any details on the mission of the helicopter, a UH-60 Black Hawk.

US officials said three of the seven American troops killed were special operations forces - two Navy SEALS and a Navy explosives expert. The officials spoke on condition of anonymity because they were not authorised to disclose the information.

Taliban spokesman Qari Yousef Ahmadi said insurgent fighters shot down the helicopter in Kandahar province on Thursday morning.

"Nobody survived this," Ahmadi told The Associated Press by phone.