President Hamid Karzai ordered a probe Wednesday into allegations by local officials that more than 30 civilians were killed this week in a bombing by U.S.-led troops battling militants in western Afghanistan.

Karzai, currently in the United States, will raise the issue of civilian deaths with President Barack Obama, a statement from Karzai''s office said. The two presidents were scheduled to hold their first face-to-face meeting later Wednesday.

Civilian deaths have caused increasing friction between the Afghan and U.S. governments, and Karzai has long pleaded with American officials to reduce the number of civilian casualties in their operations. U.S. and NATO officials accuse the Taliban militants of fighting from within civilian homes, thus putting them in danger.

Local officials said Tuesday that bombing runs called by U.S. forces killed dozens of civilians in Gerani village in Farah province''s Bala Buluk district.

A joint U.S.-Afghan delegation left for Farah on Wednesday to investigate the incident, the president''s office said.

"President Karzai said that the civilian casualties are unacceptable and he is going to raise the issue with high-level U.S. officials, including President Barack Obama," the statement said.