U.S.-led coalition troops clashed with a group of Taliban fighters in northern Afghanistan on Sunday, killing six militants, while four militants were killed in a battle in the south, officials said.

President Hamid Karzai, meanwhile, fired two Afghan army officers following a joint Afghan-coalition operation in the country's west that he said killed at least 89 civilians.

In the north, coalition troops returned fire after being attacked by militants while on patrol in the volatile Tagab valley of Kapisa province, said coalition spokesman 1st Lt. Nathan Perry.

Rahimullah Safi, the province's deputy governor, said six militants were killed in the clash, while Perry said "multiple militants" were killed.

Tagab is close to where militants killed 10 French troops Tuesday in the deadliest ground attack on foreign troops since the Taliban were ousted from power in 2001.

In southern Helmand province Sunday, four militants were killed by NATO aircraft and Afghan troops, the military alliance said in a statement.

Troops fired on the militants after they attacked an Afghan army unit that was guarding a satellite station in Helmand's Musa Qala district, the statement said.

In the eastern Kunar province, a civilian Mi-8 supply helicopter contracted by NATO-led troops crashed shortly after takeoff Sunday, killing one person on board and wounding three others, the alliance said in a statement.

It said the helicopter was leaving a NATO base in the area when it crashed. The alliance did not release the nationalities of the civilians or say what caused the crash.

Separately, three civilians were killed and seven others wounded when their vehicle was hit Sunday by a roadside bomb in the eastern Khost province, said Abdul Qayum Bakizoy, the provincial police chief.

Bakizoy blamed "enemies of Afghanistan" for planting the bomb.

More than 3,400 people — mostly militants — have been killed in insurgency-related violence this year, according to figures from Western and Afghan officials.

Karzai ordered the Defense Ministry to investigate Gen. Jalandar Shah, the corps commander for the Afghan National Army in Herat, and Maj. Abdul Jabar, the commander of the commando unit involved in the Friday raid in Azizabad village of Herat's Shindand district.

An Afghan human rights group that visited the site of the operation said Saturday that at least 78 people were killed in clashes and an airstrike. The Ministry of Interior has said 76 civilians died, including 50 children under the age of 15, though the Ministry of Defense said 25 militants and five civilians were killed.

Karzai said Sunday that at least 89 civilians were killed.

Originally the U.S. coalition said the battle killed 30 militants, including a wanted Taliban commander, but U.S. coalition spokeswoman Rumi Nielson-Green said Saturday that five civilians — two women and three children connected to the militants — were among the dead.

The U.S. said it would investigate.