JALALABAD: A suicide bomb blast in Afghanistan's eastern city of Jalalabad killed 33 people and injured more than 100 outside a bank where government workers collect salaries, the city's police chief said on Saturday.

Police were investigating whether there was a second explosion after people rushed to the scene to help, the police chief, Fazel Ahmad Sherzad, told a news conference.

“It was a suicide attack,” Sherzad said, adding that police had yet to determine if the attacker had worn the explosives or had placed them in a car. “It is early to say what kind of suicide bomber.”

Taliban insurgents denied responsibility, although they have claimed earlier killings in a wave of attacks coinciding with the sharp drawdown of foreign troops.

“It was an evil act. We strongly condemn it,” the Islamist militants' spokesman, Zabihullah Mujahid, told Reuters.

Afghan President Ashraf 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.

For the first time since the hardline Islamist Taliban movement was ousted from power in 2001, Afghan forces are fighting with little support from Nato troops. Nato, which at its peak had 130,000 soldiers in Afghanistan, has only a few thousand left, involved mainly in training and special operations.

Police said a third blast that shook Jalalabad was a controlled detonation after experts discovered another bomb close to the scene of the first explosion.

Earlier this month, a suicide bomber killed at least 16 people and wounded 40 others, including a prominent lawmaker, at an anti-corruption rally in eastern Afghanistan.

Also read: Bomb attack kills 16, wounds 40 in Afghanistan

The attack came just a week after Washington announced it would not be halving the 9,800 US troops still in Afghanistan by the end of the year, backpedalling on previous plans.

The Taliban, waging a deadly insurgency since they were ousted from power in late 2001, had warned that the US troop announcement would damage any prospects of peace talks as they vowed to continue fighting.

The number of civilians killed and wounded in Afghanistan jumped 22 per cent in 2014, a recent UN report said, as Nato troops withdrew from combat.

The United Nations Assistance Mission in Afghanistan attributed the rise to an intensification in ground fighting, resulting in a total of 10,548 civilian casualties last year.

A US watchdog said in a report last month that Afghan security forces were suffering heavy casualties on the battlefield and large numbers of troops were resigning or deserting their units.

Between October 2013 and September 2014, more than 1,300 Afghan army soldiers were killed in action and 6,200 were wounded, the Special Inspector General for Afghanistan Reconstruction (SIGAR) said in its report. Between September 2013 and September 2014, more than 40,000 personnel were dropped from Afghan National Army rolls, it added.

The Pentagon insists the Afghan forces are holding their own after the bulk of NATO combat forces withdrew last year. But senior US officers have voiced concern at the high casualty and attrition rates plaguing the Afghan army.