Afghanistan's intelligence agency has blamed the Haqqani network, a Pakistan-based armed group aligned with the Taliban, for a suicide bombing that killed more than 60 people at a volleyball match near Afghanistan's eastern border.
Haseeb Sediqi, spokesman for the National Directorate of Security, claimed to have evidence showing the group was responsible for the Sunday attack at an inter-district tournament match attended by a large crowd in the Yahya Khel district of Paktika province.
"We will release more information shortly," he told reporters on Monday.
Officials said at least 61 people were dead and about 60 more were wounded in the attack, adding that most casualties were civilian. The suicide bomber was on foot in the crowd, authorities said.
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Al Jazeera's Charles Stratford, reporting from Kabul, confirmed that authorities have blamed the Haqqani network for the attack, but noted there has not been an admission of responsibility by the group.
"What we know about the Haqqani network is that they are based in Pakistan and they do operate across the borders," he said.
"They have strong ties with the Taliban and al-Qaeda and have launched some of the most devastating attacks here in Afghanistan in recent years."
International Olympic Committee President Thomas Bach condemned the "cowardly" attack.
"It is an attack on sport itself and on the positive values it can bring to help build strong communities and foster peace and reconciliation around the world," he said in a statement.
Pakistan also condemned the deadly attack. "No cause justifies such acts of terrorism and taking of innocent lives," its foreign ministry said in a statement.
The Taliban and other fighters have mounted multiple suicide attacks and assassinations in Afghanistan this year, as foreign forces continue to withdraw after 13 years of war.
Sunday's attack is one of the deadliest so far this year, a time when attacks are escalating following a controversy-marred election and the inauguration of President Ashraf Ghani in September.
Afghanistan's parliament approved agreements on Sunday with the US and NATO allowing international troops to remain in the country past the end of this year.
According to the deals, about 12,000 international troops will remain in Afghanistan next year to train and support Afghanistan's security forces.
Ghani's first act after becoming president was to sign the agreements, which are opposed by the Taliban and other armed groups.
US President Barack Obama wants all American troops to be out of Afghanistan by the end of 2016, as his presidency draws to an end.
Source: Al Jazeera and agencies