Gunmen stormed a government building after multiple explosions in an ongoing attack in Jalalabad on Tuesday that has left at least 11 people wounded, the latest in a series of assaults in the eastern Afghan city.

On the other side of the country a roadside bomb apparently intended for security forces hit a passenger bus and killed at least 11 people, as civilians once again bear the brunt of violence in Afghanistan.

In the attack in Jalalabad at least two blasts were heard before the attackers entered the compound of the refugees and repatriations department, said Attaullah Khogyani, spokesman for the governor of Nangarhar province.

Several foreign organisations are also in the vicinity.

As the attack began, representatives of foreign donors and agencies were wrapping up a meeting with department employees inside the building, Khogyani said.

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

"The operation to rescue more people possibly stuck in the building is also ongoing," he added.

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

"We don't know the exact number," he added.

At least 11 people have been wounded and a "large number" of employees had been rescued, Khogyani said.

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

At least one of the men blew himself up at the gate and two others entered the building, the witness said.

Khogyani said one of the two attackers had been killed.

An AFP reporter could hear gunfire as 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 attack 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.

The Islamic State group claimed responsibility for Saturday's attack, which left at least three people dead and several wounded.

Jalalabad has been the scene of multiple attacks in recent months that have killed dozens, as US and Afghan forces continue offensives against militants.

Civilians under attack

In the western province of Farah on Tuesday 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.

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.

On July 11 gunmen raided an education department compound in Jalalabad, sparking an hours-long battle with security forces.

At least 11 people were killed in the attack. All were employees of the education department branch and included the director.

A suicide bomb attack claimed by IS on a crowd of Afghan Sikhs and Hindus in Jalalabad on July 1 killed 19 people and wounded 21.

IS emerged in Afghanistan in 2014 and quickly established a stronghold in Nangarhar, which borders Pakistan.

Intensified aerial and ground operations against the militants have failed to dislodge them.