A UN committee has expressed "alarm" over reports that hundreds of children have been killed by US military forces in Afghanistan in the past five years.
The Geneva-based Committee on the Rights of the Child (CRC) said the deaths were "due notably to reported lack of precautionary measures and indiscriminate use of force".
The report, received by AFP on Friday, also expressed concern that troops responsible for the killing of children had not always been held accountable and that family grievances had not been redressed.
The CRC's comments came after a five-yearly review of US compliance with an international treaty on the involvement of children in armed conflict.
It said it was "alarmed at reports of the death of hundreds of children as a result of attacks and air strikes by the US military forces in Afghanistan over the reporting period".
"The committee expresses grave concern that in fact the number of casualties of children doubled from 2010 to 2011."
There was no immediate reaction from the United States. State Department spokeswoman Victoria Nuland told reporters on Thursday that she had not seen the report, but would look into it.
A UN report in April last year said 110 children were killed and 68 wounded in airstrikes conducted by US-led NATO and Afghan National Security Forces in 2011.
The CRC report gave no precise statistics.
"The US can and should do more to protect children affected by armed conflict," said Jo Becker, children's rights advocacy director at Human Rights Watch, a watchdog based in New York.
She called on the US to heed the committee's recommendations, which include taking "concrete and firm precautionary measures and prevent indiscriminate use of force" to ensure that no more civilians and children are killed.
UN figures show that the vast majority of civilian casualties in the Afghan war are caused by Taliban insurgents, mainly through roadside bombs and suicide attacks.
But those caused by NATO forces have long been a cause of friction with the government of President Hamid Karzai.