Afghan officials say a commercial flight carrying at least 43 passengers crashed Monday in the northern part of the country. The U.S.-led NATO force is involved in search and rescue efforts.

NATO's International Security Assistance Force (ISAF) says bad weather is hampering its efforts to help Afghan officials locate the plane and rescue any survivors in the mountainous region where it apparently crashed.

Pentagon Spokesman Bryan Whitman outlined the U.S. and international involvement.

"ISAF is providing some search and rescue [capability] now for that, in terms of helicopter support, rotary aircraft, as well as, early on, some help in identifying the location that it went down," he said.

Whitman says it is too early to determine the cause of the crash, or to provide any other details.

Afghan authorities say the Pamir Airways flight went down early Monday while on its way from the northern city of Kunduz to the capital, Kabul.

An Afghan security man stands near the mountains w
An Afghan security man stands near the mountains where an Afghan Pamir Airways plane is believed to have crashed in the Salang pass, north of Kabul, 17 May 2010

A release by the NATO command in Kabul says it dispatched two helicopters to the area, and has more on standby for deployment from the capital and from the Air Base at Bagram. It says it also sent a larger fixed-wing aircraft to help in the search area, near the Salang Pass in the Hindu Kush mountains.

An Afghan official said his government had also asked for unmanned aircraft to help in the search.

Such aircraft can fly for longer periods than manned planes, and could endure difficult conditions, without endangering a pilot. Equipped with powerful lenses and the ability to send real-time video to ground controllers, the unmanned planes have played a crucial role in finding, following and even killing suspected insurgents in Afghanistan and Pakistan in recent years.