UNITED NATIONS — U.S. military attacks in Afghanistan, including drone strikes, have reportedly killed hundreds of children over the last four years, according to the U.N. body monitoring the rights of children.

The Geneva-based Committee on the Rights of the Child said the casualties were "due notably to reported lack of precautionary measures and indiscriminate use of force."

The group scrutinized a range of U.S. policies affecting children for the first time since 2008 — the last year of the Bush administration and the year Barack Obama was first elected president.

The U.N. review is conducted every four years, and the report's release came as U.S. policy on drone targeting and airstrikes is under intense scrutiny in Washington.

John Brennan, the White House counterterrorism chief who is Obama's choice to head the CIA, faced a Senate Intelligence Committee confirmation hearing Thursday.

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Brennan helped manage the drone program and defended targeted killings by drones and airstrikes as a more humane form of warfare that results in fewer collateral casualties.

A report to the U.N. Security Council last April by Secretary General Ban Ki-moon's special representative for Children and Armed Conflict said, "The number of child casualties attributed to airstrikes conducted by pro-government forces, including the Afghan National Security Forces and the International Military Forces, doubled compared with the last reporting period, with 110 children killed and 68 injured in 2011."

The United States provides air power for the government of Afghan President Hamid Karzai.

State Department spokeswoman Victoria Nuland said Thursday that she was not aware of the U.N. report and would look into it.

In its report, the U.N. committee told the United States to "take concrete and firm precautionary measures and prevent indiscriminate use of force to ensure that no further killings and maiming of civilians, including children, take place."

Human rights and civil liberties groups applauded the U.N. committee's findings and recommendations.

"The U.S. must also honor its international law obligations to thoroughly and independently investigate civilian deaths and abuses against children, hold perpetrators accountable and compensate victims," Jamil Dakwar, director of the American Civil Liberties Union's Human Rights Program, told The Associated Press on Thursday.