The blast occurred on Friday when the prayer was going on and left 60 others hurt.

US ambassador John Bass tweeted: " I condemn the intentional attack against the mosque in Nangahar and offer my condolences to the victims and their families. Killing worshippers assembled together in peace is unconscionable. All #Afghans have the right to live and worship together in safety."

The European Union said: "The European Union presents its sincere condolences to the families of the victims of today’s terror attack on Muslims attending their weekly prayers at a mosque in Nangahar province. We wish a speedy recovery to those injured."

British Embassy in Kabul city said: "Utterly condemn the deaths of worshippers during Friday prayers. The violence needs to stop."

The attack on a mosque in Nangarhar province, eastern Afghanistan, which resulted in scores of civilians being killed, and dozens more injured, has been strongly condemned by UN chief António Guterres.

In a statement released on Friday, Guterres declared that those responsible for the attack must be held accountable. He extended his deepest sympathy and condolences to the families of the victims, and wished a speedy recovery to those injured.

The Secretary-General reiterated the solidarity of the United Nations with the people and Government of Afghanistan.

Pakistan's Ministry of Foreign Office also condemned the incident and said in a statement and said: "We share the grief of the bereaved families and offer our deepest sympathies and condolences over their loss in this mindless act of terrorism. Our thoughts and prayers are with the victims and their loved ones in this difficult time."

"Pakistan condemns terrorism in all its forms and manifestations and stands in solidarity with the government and people of Afghanistan in their fight against terrorism," it said. 

No group has claimed responsibility for the incident so far.

High rate of civilian casualty in Afghanistan:

Afghanistan has seen record-high levels of civilian casualties in the third quarter of 2019, stemming mainly from the violence between rival political party supporters, the UN Assistance Mission in the country (UNAMA) revealed in a report published Thursday, which concluded that more must be done to protect the country’s people.

In just the first nine months of 2019 overall, UNAMA counted more than 8,200 civilian casualties - 2,563 killed and 5,676 injured - similar to figures in the corresponding nine-month periods from 2014 onwards. But the last three months, has seen an “unprecedented number of civilian casualties”, UNAMA said.

In July, the Mission documented the country’s bloodiest month on record, with the highest number of civilian casualties in a single month since the UN began systematic documentation in the country, in 2009.

“Civilian casualties at record-high levels clearly show the need for all parties concerned to pay much more attention to protecting the civilian population, including through a review of conduct during combat operations,” said Tadamichi Yamamoto, the Secretary-General’s Special Representative for Afghanistan.

The harm done signals the importance of peace talks for a ceasefire,  Yamamoto added, calling for a political settlement to the conflict. “There is no other way forward”, he said.