The U.S. military on Wednesday defended an airstrike earlier this week on a southern Afghan village that killed at least 16 civilians, saying its troops were being fired on and they had the right to defend themselves.

Meanwhile, 60 Taliban militants and four Afghan soldiers were killed Tuesday evening in the latest firefight in southern Afghanistan, which also involved coalition airstrikes, said Afghan army Gen. Rehmatullah Raufi.

U.S. military spokesman Col. Tom Collins also apologized to the families of the victims of the assault late Sunday and early Monday, saying "we never wanted this to happen." He said the coalition has offered assistance to the families, but didn't disclose any details.

"The ultimate cause of why civilians were injured and killed is because the Taliban knowingly, willfully chose to occupy homes of these people. We do everything we can to prevent killing civilians," he told reporters in Kabul.

The airstrike was one of the deadliest since the American-led invasion in 2001, and Afghan President Hamid Karzai has ordered an inquiry, the second time in five weeks the leader has complained about civilian deaths from airstrikes.

The military has confirmed the deaths of 20 militants in the assault on the village of Azizi and believes up to 60 more may also have died. Collins said some unidentified local Taliban leaders may be among the dead.

Collins said the military estimate of the number of civilian deaths was the same as that of Asadullah Khalid, the governor of Kandahar, who has said at least 16 died.

Collins said the troops did not know there were civilians in the homes when the U.S. military called in Air Force A-10 Warthogs to strafe the buildings with large-caliber bullets.

Human rights advocates criticized both the U.S. airstrike and the Taliban's tactic of hiding behind civilians.

"Taliban insurgent forces who take shelter in a civilian area knowing that it's going to draw hostile fire are violating international law," said Sam Zarifi, head of New York-based Human Rights Watch's Asia division.

The number of casualties in the latest fighting Tuesday in southern Uruzgan province was difficult to confirm independently because the scene of the fighting was remote and could not be immediately reached. Raufi said three Afghan soldiers were also wounded.

Coalition airstrikes were called in toward the end of the battle, said Raufi. A spokesman for the coalition couldn't immediately confirm this.

The fighting began in a small village in Tirin Kot district before the militants fled higher into the mountains, Raufi said. It was there that airstrikes bombed Taliban positions, he said.

In the past year, Uruzgan has been the site of some of the heaviest fighting in Afghanistan, but militants suffered high losses in multiple battles with coalition forces, and the violence there has subsided in recent months.

Militants have stepped up attacks in the last several months, particularly in Afghanistan's southern and eastern regions near its border with Pakistan. Thousands more NATO forces are scheduled to move into the areas later this summer.

Collins said Taliban rebels have grown in "strength and influence" recently and now have a hard core of fighters in southern Afghanistan.

"There is a hard-core group of Taliban fighters, certainly numbering in the hundreds," he told reporters in Kabul. "We know for a fact that in recent weeks they have grown in strength and influence in some parts of Kandahar, Helmand and Uruzgan" — three southern provinces most wracked by the insurgency.

He said the militants were recruiting poor villagers.

"They prey upon people who don't have a lot of hope," he said. "These people may not believe much in the cause, but they need a job."