Afghan officials say a NATO helicopter strike Saturday killed at least one child near the capital of Ghazni province.

Other reports said two children had died. Officials said the helicopter strike also killed at least nine Taliban fighters. The NATO-led force in Afghanistan said it was aware of the reported civilian casualties and was assessing the incident.

Civilian casualties have been one of the most sensitive issues in relations between Afghan President Hamid Karzai and international forces.

Due to another sensitive issue, the U.S. military Saturday pulled out of a strategic district of eastern Afghanistan, handing security responsibility over to Afghan forces. The troops' withdrawal from the district of Nerkh in Wardak province was part of a deal with President Karzai following allegations that Afghan forces had committed human rights abuses there under U.S. orders. The charges involved the torture and murder of militant suspects in the area -- charges U.S. officials denied.

In a statement on the U.S. troop withdrawal from Nerkh, General Joseph Dunford, the top commander of U.S. and NATO forces in Afghanistan, said the rest of Wardak province will "continue to transition over time."

Afghan forces are scheduled to take over full security responsibility in Afghanistan by the end of 2014, when most coalition forces are set to be out of the country.

Separately Saturday, President Karzai traveled to Qatar to discuss the potential for future peace talks with the Taliban.