KABUL : A helicopter on contract to NATO-led forces crashed Tuesday in southern Afghanistan, killing six civilians on board and an Afghan child on the ground. NATO said the cause of the crash was under investigation but the owner reported it was shot down.

Also Tuesday, officials said two U.S. Marines and an Italian soldier had been killed in the latest fighting.

The helicopter slammed into the ground and caught fire at daybreak in Helmand province's Sangin district, said Fazel Haq, the top district official.

Six civilians on board were killed and an Afghan national on the ground was injured, said a spokesman for the NATO-led force, who could not be identified because he was not the media office's top spokesman.

A child on the ground was also killed, said Daud Ahmadi, a spokesman for Helmand's governor.

In the former Soviet republic of Moldova, the government aviation authority said the Mi-26 helicopter was performing a humanitarian mission when it was struck by a missile or a rocket. The six-member crew were Ukrainians, a statement said.

The Taliban claimed to have shot down a helicopter with dozens of British troops aboard. NATO and Moldovan authorities said no one was aboard except the crew.

Elsewhere in the south, two U.S. Marines were killed in a "hostile incident" on Monday, said U.S. military spokeswoman Capt.

Elizabeth Mathias. She did not provide any other details.

Some 4,000 Marines are pushing through Helmand province in the biggest U.S. military operation in Afghanistan since the ouster of the Taliban from power in 2001. The region is the world's largest opium poppy producing area and the Taliban's heartland.

Taliban fighters have planted dozens of roadside bombs in the region, one of the greatest threats to troops operating there.

Militants have increased their attacks dramatically in the last three years.

The two deaths bring to 107 the number of U.S. troops killed in Afghanistan so far this year, compared with 151 U.S. deaths in all of 2008. As of Monday, at least 660 members of the U.S. military had died in Afghanistan, Pakistan and Uzbekistan since 2001, according to the Defense Department. Of those, the military says 492 were killed by hostile action.

The Italian Defense Ministry said a roadside bomb killed one Italian soldier and wounded three others in western Afghanistan on Tuesday. Italy has some 2,800 soldiers in Afghanistan, mostly in Kabul and the western region of Herat.

Separately, a roadside blast Tuesday hit a civilian vehicle in Uruzgan, another southern province, killing three people and wounded six others, according to an Interior Ministry statement. It said all the victims were civilians.