KABUL, Afghanistan -- The U.S.-led international coalition says a UN rights group's concerns about reports that U.S. military strikes have killed hundreds of children during the past four years are "categorically unfounded."

Thursday's statement by the International Security Assistance Force comes a day after the Geneva-based U.N. Committee on the Rights of the Child said the casualties were largely due to the use of indiscriminate force and lack of precautionary measures.

The coalition also rejects that claim, saying it takes special care to avoid civilian casualties. The coalition says the number of children who died or were wounded from air operations dropped by nearly 40 per cent in 2012 compared with the year before.

U.S. policy on drone targeting and airstrikes is under intense scrutiny.