The Islamic State (IS) group claimed to have carried out a deadly suicide attack in eastern Afghanistan Saturday that killed at least 33 people and injured more than 100, Afghan President Ashraf Ghani said, in what, if verified, would be the first major attack claimed by the jihadist group in the country.

"Who claimed responsibility for horrific attack in Nangarhar today? The Taliban did not claim responsibility for the attack, Daesh (IS) claimed responsibility for the attack," President Ghani said on a visit to northeastern Badakhshan province.

A person purporting to be an IS spokesman said in a call to AFP that the group claimed responsibility for the bombing outside a bank in the eastern Afghan city of Jalalabad.

An online posting allegedly from the group made the same claim, which could not be immediately verified.

"Thirty-three dead bodies and more than 100 wounded were brought to the hospital," Dr Najeebullah Kamawal, head of the provincial hospital, told AFP.

Ahmad Zia Abdulzai, a provincial government spokesman, confirmed the attack -- the deadliest since November.

"The explosion happened outside the bank when government employees and civilians were collecting their monthly salaries," he told AFP.

The UN gave a higher toll, saying 35 people had been killed.

READ: Suicide bomber kills 33 outside Afghan bank

President Ghani strongly condemned the attack, which saw children among those killed, his office said in a statement.

"Carrying out terrorist attacks in cities and public places are the most cowardly acts of terror by terrorists targeting innocent civilians," President Ghani said.

The scene of the attack showed the gruesome scale of the carnage with people lying in pools of blood and body parts scattered across the ground.

The bombing comes as Afghanistan braces for what is expected to be a bloody push by the Taliban at the start of the fighting season.

However, Taliban spokesman Zabihullah Mujahid denied responsibility.

The militants have stepped up attacks on government and foreign targets since Washington backpedalled on plans to shrink the US force in Afghanistan this year by nearly half.

The Taliban have seen defections to IS in recent months, with some insurgents voicing their disaffection with their one-eyed supreme leader Mullah Omar, who has not been seen since the 2001 US-led invasion of Afghanistan.

The Afghan government has also raised the ominous prospect of IS making inroads into the country, though the group that has captured swathes of territory in Syria and Iraq has never formally acknowledged having a presence in Afghanistan.