The governor of Helmand province in southern Afghanistan said Sunday that NATO-led troops killed 14 civilians on Saturday night and 12 children were among the dead.

The governor said the bomb also killed two women and bereaved relatives brought the children’s bodies to the provincial capital to protest.

It was one of the deadliest foreign assaults on Afghan civilians in recent several months, according to a China Daily report.

Afghan President Hamid Karzai condemned the killing from NATO air strikes, saying he had warned the US and NATO troops that their "arbitrary and unnecessary operations" were killing innocent people "every day."

US President Barack Obama's spokesperson said after the air strike that the White House shares Karzai's concerns over civilian casualties and takes them very seriously.

The commander of the NATO-led International Security Assistance Force (ISAF) in southwestern Afghanistan apologized for the deaths of civilians.

Major General John Toolan explained that his troops had unwittingly targeted a compound because insurgents were using it as a base.

He said in a statement that "unfortunately, the compound the insurgents purposefully occupied was later discovered to house innocent civilians," China Daly reported.

Helmand is a volatile province that borders Pakistan's Baluchistan province, where Afghan and US officials believe that Taliban officials are based. In the past year, US troops in Afghanistan has put their focus on breaking the Taliban's grip there and in Kandahar, the province directly east where the Taliban movement began, World Wires reported.

Violence has risen significantly in the past month as Taliban insurgents step up their attacks against Afghan and NATO troops across the country.

The NATO-led ISAF was created in accordance with the Bonn Conference in December 2001, and currently 48 contributing nations provide more that 132,000 troops to this mission.