At least 24 people were killed on Monday when two Taliban suicide bombers on foot struck close to the defence ministry in Kabul during late afternoon rush hour, the latest assault on the Afghan capital.

Around 91 others were wounded in the assault, which comes as the Taliban intensify their nationwide offensive against the US-backed government.

"Two suicide bombers, both on foot, detonated their explosives... in downtown Kabul," interior ministry spokesman Sediq Sediqqi told AFP.

The two bombers blew themselves up in rapid succession, in an attack apparently aimed at inflicting mass casualties as government workers left the ministry after work.

"The first explosion occurred on a bridge near the defence ministry. When soldiers, policemen and civilians rushed to the scene, there was the second explosion," defence ministry spokesman Mohammad Radmanish said.

President Ashraf Ghani strongly condemned the attack.

"The enemies of Afghanistan are losing the fight in the ground battle with security forces," Ghani said in a statement. "That is why they are attacking, highways, cities, mosques, schools and ordinary people."

Taliban spokesman Zabihullah Mujahid said on Twitter that the defence ministry was the object of the first attack, while police were targeted in the second.

The double bombing came less than two weeks after gunmen attacked the American University in Kabul, killing 13 people.

It was the deadliest attack in Kabul since at least 80 people were killed by a suicide bomber who targeted a demonstration on July 23. That assault was claimed by Islamic State.

Government officials have been preparing for a conference in Brussels next month at which foreign donors, concerned about the ability of the Afghan security forces to withstand Taliban violence, are expected to pledge continuing support over coming years.

(Feature image source for representation: AFP)