U.S. forces killed at least one child, video footage obtained by Reuters on Wednesday showed, in an air strike in western Afghanistan that Afghan police say killed 12 civilians and U.S. forces said killed 16 militants.

Videos taken in the Gozara district of Herat province in the aftermath of the attack on Monday showed mangled, unrecognisable clumps of flesh - all that remained of several people and dozens of animals killed in a tented nomad encampment. One body that was recognisable was that of a young boy.

"The information we have is 12 civilians, including six women, four men and two children have been killed in the bombardment," General Ikramuddin Yawar, chief of police in western Afghanistan told Reuters.

More than 2,100 civilians were killed in Afghanistan last year, 40 percent more than 2007, the United Nations said on Tuesday, and a quarter of all civilian casualties, 552 people, died as a result of air strikes by U.S. and NATO-led forces.

International forces in Afghanistan are losing public support "one fallen civilian at a time", said a report by the Campaign for Innocent Victims of Conflict (CIVIC) on Tuesday.

News of the attack comes as U.S. President Barack Obama on Tuesday ordered 17,000 more U.S. troops to Afghanistan to try to break the stalemate against Taliban insurgents fighting to overthrow Afghan President Hamid Karzai's Western-backed government and drive out foreign forces.

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Karim Khan, one of the survivors in the Monday air raid said aircraft started bombing the area at four in the morning. "Thirteen people from the tents and three other visitors were killed."

The regional police chief said both civilians and militants were among those killed.

"There were militants among the dead, but we don't know how many yet as we are investigating the case," Yawar added.

He added that some 60 animals and 18 tents in the encampment of 100 families were also destroyed in the air raid.

SOURCE OF TENSION

But U.S.-led coalition forces said 16 militants including a wanted commander were killed in Monday's air strike.

"A coalition forces precision strike targeted Gholam Yahya Akbari, a key insurgent commander ... Killed in the attack were up to 15 militants suspected of associating with Yahya," the U.S. military said in a statement.

"Knowing he is targeted by coalition forces, Yahya shows a total disregard for human life by operating among the civilian population," U.S. forces spokesman Lieutenant Colonel Rick Helmer said in the statement.

He said there are no official reports of civilian casualties and any confirmed reports of civilian deaths would be investigated.

The United Nations said the transparency and independence of inquiries into civilian deaths by foreign and Afghan forces was a source of concern, as was the placement of military bases within urban areas were there was a high concentration of civilians.

The issue of civilian casualties is biggest source of tension between Karzai and his Western backers and has led to a steady drop in public support for the continued presence of nearly 70,000 troops in the country.

U.S. officials admit that more than seven years after U.S.-led troops toppled the Taliban for harbouring al Qaeda leaders behind the Sept. 11 attacks, Washington and its allies are not winning in Afghanistan.

Military commanders warn violence will further increase in this year as the new troops move into areas foreign forces have seldom patrolled before, and that would also likely lead to a rise also in civilian casualties.

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