Kunduz, Afghanistan: Villagers in the Afghan province of Kunduz said on Tuesday they had buried dozens of victims of a government air strike in a Taliban-controlled district, in an incident the United Nations described as ‘disturbing’.

The office of the governor of the northern province said Monday’s attack by the government air force on a Taliban meeting had inflicted an unknown number of civilian casualties.

The casualties underlined the risk of greater use of air power under a new US strategy announced last year to try to force the militant group to the negotiating table.

Sayed Jaan, a resident of the district of Dasht-i Archi, said he attended two mass funerals of almost 40 people, adding that other burials had taken place.

He said the helicopter attack happened during a religious ceremony, called Dastaar Bandi, to mark young men completing the memorization of the Koran, the Muslim holy book.

‘There were two mass graves to bury the victims of the bombing and I took part in both burials. In one grave, 16, and in another, 21. Many were young children,’ Sayed Jaan said.

‘There were other burials and people were digging graves.’

The United Nations Assistance Mission in Afghanistan (UNAMA) said in a tweet its investigators were in the area looking into ‘disturbing reports of serious harm’ to civilians.

A senior Afghan defence ministry official said the air attack happened during a meeting of militants, and killed at least 35 Taliban and wounded many more. He denied reports that civilians were harmed and said two senior Taliban commanders were among those killed.

But provincial government leaders including the governor and police had determined that the strike was against a Taliban meeting but it had also inflicted an undetermined number of civilian casualties, the governor’s office said.

The Taliban briefly seized Kunduz city in 2015 and they overran it for a second time the following year. US air strikes destroyed a Kunduz hospital in 2015 killing 42 people, most of them patients and medical staff.

The city has been considered relatively secure over the past year or two but the Taliban control much of the surrounding area.

A video posted online by the Taliban showed at least four bodies of children, wrapped in white shrouds. Other images circulated of children and adults being treated in hospital for injuries, but they could not be verified.

Building up the fledgling government air force has been a major priority for the NATO-led Resolute Support training and advisory mission.

On Monday, the Taliban said the strike killed 150 religious scholars and civilians and denied that any of their forces had been there.

Last year, more than 10,000 civilians died or were wounded in the war between Afghanistan’s Western-backed government and the militants, down 9 percent from the previous year, UNAMA said in a report in February.