At least 62 worshipers were killed and dozens wounded after a blast hit a mosque in Haska Mina district of Afghanistan's eastern Nangarhar province on Friday, a regional spokesperson said. 

"The incident occurred in Jodari at midday when two mortar shells fired by militants struck a mosque during Friday prayers and the roof of the muddy building collapsed by the force of the explosions," an anonymous source told Xinhua News.

The attack – the year's second most deadly to date – came after the UN released a new report on Thursday saying an "unprecedented" number of civilians were killed or wounded in Afghanistan from July to September.

The figures – 1,174 deaths and 3,139 injured from July 1 until September 30 – represent a 42 percent increase compared to the same period last year.

No one has claimed responsibility for the incident, but Taliban and ISIL militants control parts of the province, 120 km east of the capital Kabul.

A Taliban spokesman said the group has "condemned this atrocity in the strongest terms" and labeled it a "major crime".

About 350 worshipers were inside at the time, said local resident Omar Ghorzang.

"Dozens of people were killed and wounded and were taken in several ambulances," said Haji Amanat Khan, a 65-year-old local resident.

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.

"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.

(With input from Xinhua and AFP)