At least 69 people were killed by a blast inside an Afghan mosque during Friday prayers, according to officials, a day after the United Nations said violence in the country had reached “unacceptable” levels.

On Friday, local officials had reported 62 fatalities and about 50 wounded.

The attack, the year’s second most deadly to date, took place in the eastern province of Nangarhar and also wounded at least 50 people, the Provincial Governor’s spokesman Attaullah Khogyani said.

The blast was carried out with “explosives that were placed inside the mosque”, Khogyani said, though other sources, including the Taliban said the building may have been hit by a mortar.

A spokesman for the Islamist extremist Taliban said the group has “condemned this atrocity in the strongest terms” and labelled it a “major crime”.

Witnesses said the roof of the mosque had fallen through after a “loud” explosion, the nature of which was not immediately clear.

One of the wounded, Gulabistan (45) said the mosque was full when the explosion happened.

“Mullah already started prayers and reciting verses of holy Qur’an, when a huge boom happened, then all around me it got dark. The only thing I remember is females’ voices and then I found myself in the hospital,” he said.

He said he had been told his son was among the dead while his brother and two nephews had been wounded and were in hospital

UN Secretary General Antonio Guterres, through a spokesman, said children were among the injured.

“Those responsible for this attack must be held accountable,” the spokesman said.

The blast came after the United Nations released a new report on Thursday, saying an “unprecedented” number of civilians were killed or wounded in Afghanistan from July to September.

The report, noted the absurdity of the ever-increasing price paid by civilians given the widespread belief that the war in Afghanistan cannot be won by either side.

“Civilian casualties are totally unacceptable,” the UN’s special representative in Afghanistan, Tadamichi Yamamoto said, adding they demonstrate the importance of talks leading to a ceasefire and a permanent political settlement.

The UN laid most of the blame for the spike at the feet of “anti-government elements” such as the Taliban, who have been carrying out an insurgency in Afghanistan for more than 18 years.