KABUL (AP) — The No. 2 commanding general in Afghanistan acknowledged Wednesday that a NATO-led attack the day before in eastern Afghanistan possibly resulted in civilian deaths.

The statement that some civilians might have been killed in the attack comes amid fears among Afghan citizens that the 30,000 fresh U.S. troops being deployed to the war will result in more violence and deaths of Afghan citizens. Gen. Stanley McChrystal, the top U.S. commander in Afghanistan, has ordered troops to minimize civilian casualties, which undermine Afghan support for the war against the Taliban.

Lt. Gen. David Rodriguez, the No. 2 man, told reporters in the capital that the attack, which involved coalition and Afghan troops, was a "confusing operation."

"We're continuing to investigate," he said.

The Afghan government and NATO had differing accounts of the pre-dawn operation Tuesday in Laghman province in eastern Afghanistan.

NATO said Afghan and international forces came under fire as they assaulted the compound of a militant leader responsible for directing several suicide strikes in the region. The international force said seven insurgents were killed and four were detained, but no civilians were killed or injured.

"We are aware of civilian casualty allegations, however there are no operational reports to substantiate those claims of harming civilians, including women and children, during this operation," the NATO statement said Tuesday.

However, a statement issued by the Afghan presidential palace said six civilians were killed during the firefight, including one woman.

Local officials in the Afghan province said 12 people were killed in the clash outside Mehtar Lam, including an unspecified number of civilians. After the operation, about 400 people marched on Mehtar Lam to protest the raid, and an official said one demonstrator died in clashes with police.

U.S. Defense Secretary Robert Gates, who is touring the country, promised Afghans on Tuesday that the U.S. will do all it can to keep civilians out of the line of fire.

"Our top priority remains the safety of civilians," he said at a joint news conference with Afghan President Hamid Karzai.