An airstrike in northwest Afghanistan killed 13 Taliban militants and seven civilians Thursday, Afghan officials said, a day after President Hamid Karzai demanded a halt to civilian casualties in U.S.-led coalition operations.

The United States has conducted missile strikes in Afghanistan and in Pakistan's tribal areas along the border — strikes U.S. Gen. David H. Petraeus said Thursday have killed three of the top 20 extremist leaders there.

The strike came just days after another coalition airstrike in the south of the country killed 37 people, mostly woman and children.

The Thursday incident happened in Ghormach district of Badghis province, where a three-hour long clash between the militants and Afghan and foreign troops preceded an airstrike that hit the house of a provincial council member, said deputy governor Abdul Ghani Saburi.

Thirteen militants and seven civilians, including two women and two children, were killed in the attack, he said.

A statement from the U.S. military in Afghanistan said they are aware of "possible civilian casualties that may have occurred while responding to an insurgent ambush on a route clearance patrol in the Ghormach district of Badghis province."

"We do not know all the facts at this time but we will investigate this situation to get to the truth," said Col. Greg Julian, the chief U.S. military spokesman in Afghanistan.

"If we find that innocent people were killed in this incident, we apologize and express our sincere condolences to the families and the people of Afghanistan," Julian said.

The airstrike follows a similar incident in the southern Kandahar province, where over 30 civilians were reported killed.

Karzai on Wednesday called on U.S. President-elect Barack Obama to ensure that Afghan civilians are not killed in operations by U.S. forces, following a bombing of the remote village of Wech Baghtu in the southern province of Kandahar on Monday afternoon that destroyed an Afghan housing complex where women and children had gathered for a wedding.

Villager Abdul Jalil, a 37-year-old grape farmer whose niece was getting married, told an Associated Press reporter at the scene of the bombing that U.S. troops and Taliban fighters had been fighting about a half mile from his home.

Fighter aircraft destroyed his compound and killed 37 people, Jalil said. Karzai's office said the attack killed about 40 people and wounded 28.

Karzai referred to the deaths at a news conference held to congratulate Obama on his election victory. But the Afghan leader used the occasion to press the president-elect to prevent civilian casualties.

The U.S. military said Thursday that American and Afghan forces killed several insurgents during the incident, which started after the insurgents attacked a coalition patrol that was moving through the Shah Wali Kot region of Kandahar province between Monday and Wednesday.

Civilians "reportedly attempted to leave the area, but the insurgents forced them to remain," the U.S. military statement Thursday said. It did not say where the U.S. got that report from. It quoted Kandahar's police chief as saying several civilians were injured while attempting to leave the area.

The statement said it was "unclear if they were the victims of the high volume of insurgent direct and indirect fire." It did not say precisely how many insurgents the U.S. forces killed.

U.S. and NATO commanders often blame Taliban fighters for causing civilian casualties.

Civilian casualties, which undermine popular support for the Afghan government and the international mission, have long been a point of friction between Karzai and the U.S. or NATO.

According to an AP count of civilian deaths this year, U.S. or NATO forces have killed at least 275 civilians, while 590 have died from militant-caused violence like suicide bombs.

In one of the most serious cases of civilian deaths in Afghanistan, an Afghan government commission found that a U.S. operation in August in western Afghanistan killed some 90 civilians.

The U.S. at first denied that any civilians had been killed, but after two investigations and the emergence of photographic evidence of dozens of bodies — including children — the U.S. said that 33 civilians had died.

Petraeus, the new chief of U.S. Central Command, said the controversial airstrikes launched into Pakistan's unruly tribal areas in the last three months were a topic of conversation with every Pakistani leader he met this week. Pakistani leaders have criticized the missile strikes as a violation of their sovereignty.

"Certainly there does have to be a better explanation of the blows that have been struck in recent weeks and months," Petraeus told The Associated Press in an interview. "It is hugely important that three of 20 extremist leaders have been killed in recent months."

Petraeus did not identify the extremist leaders allegedly killed in the U.S. strikes.