A suicide bomb and gun attack by militants on an Afghan government building in Jalalabad yesterday killed at least 15 people, some burned "beyond recognition", officials said, the latest in a series of assaults on the eastern city.

On the other side of the country a roadside bomb apparently intended for security forces hit a passenger bus and killed 11 people, marking yet another bloody day for civilians who have borne the brunt of violence in Afghanistan.

The attack in Jalalabad targeted the compound of the refugees and repatriations department. It ended after more than five hours of intense fighting between militants and security forces, said Attaullah Khogyani, spokesman for the governor of Nangarhar province.

At least 15 people were killed and the same number were wounded, Khogyani said.

Provincial health director Najibullah Kamawal said some of the dead were "burned beyond recognition".

As the raid began with a suicide attacker blowing up a bomb-laden car at the entrance, local representatives of foreign donors and agencies were meeting department employees inside the building.

"All the partner agency representatives attending the meeting were Afghans and those who were stuck inside, including the director of the refugees and repatriations department, were rescued," Khogyani said.

Several people were taken hostage by the attackers, said Zabiullah Zmarary, a provincial council member.

"I saw a black Corolla car drop three armed men at the gate of the refugees and repatriations department," a witness told AFP.

Khogyani said the two attackers who stormed the compound were killed.

Security forces swarmed into the area, and a plume of thick black smoke rose into the sky above the compound.

The Taliban denied involvement in the incident in a WhatsApp message sent to journalists.

There was no immediate claim of responsibility for the attack, which comes three days after militants raided a midwife training centre in Jalalabad.

CIVILIANS UNDER ATTACK

In the western province of Farah yesterday, the bomb which hit the bus killed at least 11 people and wounded 31.

"It was a bomb planted by the Taliban to hit security forces but... it got a passenger bus," Farah provincial police spokesman Muhibullah Muhib told AFP.

There was no immediate confirmation from the Taliban that they were responsible.

An injured man leaves the area. At least two blasts were heard before the gunmen stormed a government building. Photo: Reuters

In a separate incident, 22 passengers travelling on a Kabul-bound bus in the eastern province of Paktia were kidnapped by gunmen on Monday night.

Officials blamed the Taliban for both incidents.

Most of the attacks in Jalalabad have been claimed by IS, which has a relatively small but potent presence in Afghanistan, mainly in the east and north.

It is not clear why the militants targeted the refugees and repatriations department, but government buildings are frequently hit.