KABUL, Afghanistan: A suicide bomber attacked a volleyball tournament in eastern Afghanistan on Sunday, killing at least 45 people, authorities said.

Dozens more were injured when the attacker, who was standing and mingle with the crowd, detonated his explosives, said Mokhis Afgha, the spokesman for the governor of Paktika province.

He said the attack occurred during a volleyball tournament between districts attended Yahyakhail great sang in the district late on Sunday afternoon.

"There were too many people gathered at the scene to watch the game. Dozens of people are injured and we have reports that many of them are in critical condition," said the spokesman.

"We need urgent assistance from the central government, as we may need to transfer the injured to Kabul for treatment," he added.

Paktika, which borders Pakistan, is one of the most volatile regions of Afghanistan where the Taliban-led insurgency is waging war against the government stepping in Kabul.

Sunday's attack is one of the deadliest so far this year, a time when attacks are increasing alongside a contentious election and inauguration of President AshrafGhani in September.

Afghanistan's parliament on Sunday approved agreements with the US and NATO allowing international troops to remain in the country beyond the end of this year.

Ghani's first act after becoming president was to sign the agreements, which are bitterly opposed by the Taliban and other insurgent groups.

US President Barack Obama wants all Americans to be out of Afghanistan in late 2016 troops, as his presidency comes to an end.