Hamid Karzai, the Afghan president, has accused Nato troops of killing more than 50 civilians in a troubled province of eastern Afghanistan.
Mr Karzai's statement followed comments by Fazilullah Wahidi, provincial governor of Kunar province, alleging US-led Nato forces had killed up to 63 people, including women and children in air strikes on suspected rebels.
Mr Karzai said: "about 50 civilians have been martyred during international military forces operations in Ghaziabad district in Kunar province."
Nato said they would investigate the allegations.
"We are conducting an immediate assessment of these allegations and will report our findings," said US Army Colonel Patrick Hynes in a statement.