KABUL, Afghanistan - Witnesses said Sunday that clashes between coalition troops and Taliban fighters in southern Afghanistan left at least 18 civilians dead. NATO officials, however, said no noncombatants were killed.

The alleged civilian deaths occurred in the southern Helmand province. Coalition and Afghan troops clashed late Saturday with militants near the Taliban-controlled town of Musa Qala.

A spokeswoman for NATO's International Security Assistance Force said that 12 militants were killed during the overnight clash, which started after Taliban ambushed the joint coalition and Afghan army patrol 15 miles south of Musa Qala.

But Haji Abdul Manan Agha, the tribal leader from the area, said two homes were bombed by coalition forces late Saturday. "In one home 18 people attending an engagement party were killed, including women, children and men," he said.

In the second house, eight Taliban were killed, he said. More than 30 people were wounded in both strikes, Agha said.

Mohammad Gul, a taxi driver who brought six wounded to a nearby hospital, also said that 18 civilians were killed in the clash.

Mohammad Nabi, whose relatives were among the wounded, said dozens of people were killed. "If the Taliban shoot at NATO or American convoys, than NATO and Americans come back and bomb all of the area," Nabi said. "And when we bring our casualties to the hospital then they say they are Taliban," he said.

The claims could not be independently verified due to remoteness of the area where the clash took place.

Afghan President Hamid Karzai has repeatedly deplored civilian deaths caused by NATO or U.S. military action, saying more must be done to prevent such casualties. But military officials have begun saying that some reports are nothing but information warfare by the Taliban.

Coalition and Afghan government officials have said that it is easy for Taliban fighters to falsely claim that civilians were killed by Western or Afghan military action and that militants are forcing locals to lie to journalists.

Meanwhile, 12 Taliban fighters were killed by artillery fire along the Pakistan-Afghanistan border after insurgents attacked a military post with rockets and mortars, officials said.

Coalition and Afghan troops in eastern Paktika province were attacked by insurgents who used Pakistan's territory to fire rockets and mortar rounds toward a coalition observation post Saturday, a coalition statement said.

Pakistani authorities gave permission for the troops to return fire, it said.

"Coalition counter-fire batteries destroyed the six confirmed insurgent firing sites, three on each side of the Pakistan-Afghanistan border," the statement said, adding 12 Taliban were killed.

Insurgents move back and forth through the porous border regions between Afghanistan and Pakistan.

Afghan authorities have accused Pakistan in the past of not doing enough to prevent the movement of militants across the border to attack Afghan and foreign troops in the country.

Pakistan denies the charge and says it has deployed tens of thousands of the troops along the volatile frontier to stem the flow of militants.

Violence in Afghanistan has risen sharply during the last two months. This year more than 3,800 people -- most of them militants -- have died, according to an Associated Press tally of casualty figures provided by Western and Afghan officials.