Afghan President Hamid Karzai has forcefully condemned the killing of 14 civilians in the south-west of the country in a suspected Nato air strike.
Mr Karzai said his government had repeatedly asked the US to stop raids which end up killing Afghan civilians and this was his "last warning".
A Nato spokesman said a team had been sent to Helmand province to investigate the attack carried out on Saturday.
Afghan officials say all those killed were women and children.
The strike took place in Nawzad district after a US Marines base came under attack.
The air strike, targeted at insurgents, struck two civilian homes, killing two women and 12 children, reports say.
"The president called this incident a great mistake and the murdering of Afghanistan's children and women, and on behalf of the Afghan people gives his last warning to the US troops and US officials in this regard," his office said.
The White House said it shared Mr Karzai's concerns and took them "very seriously".
A group from Sera Cala village travelled to Helmand's capital, Lashkar Gah, bringing with them the bodies of eight dead children, some as young as two years old, says the BBC's Quentin Sommerville in Kabul.
"See, they aren't Taliban," they chanted as the carried the corpses to local journalists and the governor's mansion.
While insurgents are responsible for most civilian deaths in Afghanistan, the killings of Afghans by foreign soldiers is a source of deepening anger, our correspondent adds.
President Hamid Karzai has criticised Nato for not doing enough to prevent such deaths, especially during "night raids" and has called on the country's ministry of defence to stop what he described as "arbitrary" operations by foreign forces.
In the country's north, security was extremely tight for the funeral of Gen Mohammad Daud Daud, the police commander for northern Afghanistan who was killed in a suicide bomb attack on the provincial governor's compound in Takhar province on Saturday.
He was one of at least six people killed in the attack, which was claimed by the Taliban.
The location of the funeral itself was not announced in advance for security reasons.
Shopkeepers closed their doors and hung pictures of the general as he was buried, and mourners waved black flags in his honour, Reuters news agency reports.
The governor of Takhar province, Abdul Jabar Taqwa, dismissed allegations that "rogue" elements were involved in Saturday's attack in Taloqan.
He said intelligence officials knew about the mission and even had the telephone number of the suicide bomber several days before his attack.
"We sadly failed to catch him before he could carry out his mission," the governor, whose face and hand were burnt in the attack, told reporters in Taloqan on Sunday.