Russian media say the aircraft was an Mi-8 similar to this
A civilian helicopter has crashed in southern Afghanistan, killing at least 16 civilians and injuring five, Nato officials have confirmed.
The helicopter crashed at Kandahar airfield apparently as it was trying to take off, though Nato has ruled out the involvement of insurgents.
Reports from Moscow say the helicopter was a Russian-built Mi-8.
The crash is the second in a week. Six passengers died when a helicopter came down in Helmand province on Tuesday.
'Not shot down'
Russia's Interfax agency quoted a spokesman for Russia's Federal Air Transportation Agency (Fata) as saying the aircraft was a Russian-built Mi-8 transport helicopter.
Fata said it was owned by the Russian air company Vertical-T.
The nationalities of the dead are not yet known.
A statement from Nato's International Security Assistance Force said: "A civilian contracted helicopter crashed during take-off from Kandahar airfield.
"Emergency personnel are on the scene. There was no indication of the cause of the accident but insurgent action has been ruled out."
Kandahar airfield is Nato's largest air base in southern Afghanistan but the BBC's Martin Patience in Kabul says a lot of civilian aircraft fly in and out so there is no surprise this was a civilian crash.
A Nato spokeswoman, Lt Cmdr Sam Truelove, told the AFP news agency it had been confirmed that all the dead were civilians and no military personnel were involved.
RECENT HELICOPTER CRASHES
14 Jul 2009: Six Ukrainian civilians and Afghan girl die in crash in Helmand. Suspected enemy fire
6 Jul 2009: One UK and two Canadian soldiers die in crash in Zabul province. Enemy fire not suspected
15 Jan 2009: Afghan general and 12 other soldiers die in crash in Herat province. Bad weather blamed
30 May 2007: Seven killed as Nato Chinook crashes in Helmand. Cause unclear
The condition of the injured was not known, she said.
Vertical-T was founded in 1992 and started to work abroad in 1998 in Italy. It has worked in countries including Germany, East Timor, Cyprus, Yemen and Greece, according to the company's website.
The company's helicopters are currently carrying out operations in the interests of the UN in Afghanistan and a number of other countries including Congo, Sudan and Pakistan.
The dead in Tuesday's crash in Helmand were all civilians.
That helicopter crashed near the Sangin military base, with local people saying it had been shot down by insurgents.
Six Ukrainian crew members of the Mi-26 helicopter died, along with an Afghan girl on the ground.