Afghan government and foreign military officials sparred Tuesday over reports that 10 civilians died during a military operation _ claims that further inflamed public sentiment against the international military presence as thousands more troops prepare to deploy.

Also Tuesday, NATO said a U.S. service member died in a shooting in western Afghanistan.

Afghan President Hamid Karzai said he was angered over the deaths of innocent civilians on Sunday in a village in the Narang district of Kunar province that he said included eight young students. A NATO official said initial reports from troops involved in the fighting said the victims were insurgents.

Civilian deaths are one of the most sensitive issues for foreign troops in Afghanistan. Although far more civilians are killed by the Taliban, those blamed on international forces spark widespread resentment and undermine the fight against the militants.

Earlier this year, Gen. Stanley McChrystal, the commanding officer in Afghanistan, gave his forces a new set of orders aimed at minimizing civilian casualties, though he acknowledged that doing so "entails risk to our troops." But alienating the Afghan population is a far greater risk, he said.

Shoring up Afghan support is especially important now, as some 37,000 U.S. and NATO troops will begin deploying to the country in the coming months.

The reported incident in Kunar is the most serious allegation of accidental killings of civilians by Western forces since early December, when Afghan officials said 12 civilians were killed in an airstrike in neighboring Laghman province. NATO initially denied the charge, but days later, Lt. Gen. David Rodriguez, second-in-command to McChrystal, acknowledged that an alliance-led attack might have resulted in civilian deaths. An investigation into the incident continues.

A delegation of government officials and lawmakers, appointed by Karzai, met with local officials in Kunar province on Tuesday to investigate the latest allegations.

"The president was deeply saddened and angry when he heard this news," Karzai's spokesman Waheed Omar said.

In an illustration of anti-Western sentiments in the country, an independent youth group planned a demonstration Wednesday in Kabul "against killing of civilians, especially the recent killing of students in Kunar by foreign forces."

A NATO official said that Sunday's mission in Kunar was a joint, ground operation involving U.S. and Afghan forces and no aircraft was used. The official sought anonymity so as not to interfere with coalition's involvement in the Afghan-led investigation of the incident.