The reports come as civilian deaths from air strikes have risen sharply in the past year, after the Afghan and US forces intensified their aerial bombardment of Taliban and Islamic State group militants.

Afghan forces backed by US air power were conducting counter-terrorism operations in Sangin district late Wednesday when the air strike was carried out, the ministry and NATO said.

"Some reports have been published that civilians were killed and wounded, and the defence ministry formed a delegation to conduct a serious investigation into the civilian casualties," the ministry statement said.

NATO's Resolute Support mission in Afghanistan said the "large Afghan-led, multi-day operation... supported by US advisors and coalition air strikes" was ongoing, and that it was still looking into the claims.

But the United Nations Assistance Mission in Afghanistan (UNAMA) said the reports of civilian casualties, including children, were "credible", and that it was also investigating.

"I have got reports from the residents of the area where the strike took place. Sixteen people -- ten children, four women, two men, all civilians -- were killed," Afghan senator Hashim Alkozay told AFP.

Helmand provincial governor Mohammad Yasin said the strike "also hit an adjacent civilian house".

"A number" of Afghans were killed and wounded, he added.

The strike came as Taliban representatives were meeting with US officials in Qatar this week, with four straight days of discussion raising expectations as both sides seek a way out of the 17-year Afghan conflict.

Civilians continue to pay a disproportionate price in the fighting.

UNAMA says the number of Afghan civilians killed by aerial bombings from January until October 2018 reached a record high of 313, with a further 336 wounded.

The figures represent an increase of 39 percent compared to the same time period in 2017.

UNAMA data shows that in total, 2,798 civilians were killed and 5,252 wounded in the first ten months of 2018.

The Taliban are responsible for about half of civilian casualties, with the remaining deaths attributed to the Islamic State group and coalition strikes, according to the report.

UNAMA is due to publish its full year report on civilian casualties in 2018 next month.