Militants have stormed an office of Save the Children in the eastern Afghan city of Jalalabad, and fought security forces who surrounded the building.

A local government spokesman said the siege was over after a three-hour battle. At least two people, including a soldier, are said to have been killed, and more than a dozen injured.

The attack is said to have begun with a suicide car bomb outside the office, before gunmen burst into the compound and fought with Afghan security forces.

"According to first reports, the attackers were wearing security forces' uniforms, " provincial spokesman Ataullah Khogyani told the AFP news agency, adding that "clean-up operations" were underway.

He was quoted later as saying that a civilian and a soldier were dead and 14 injured people had been taken to hospital.

Earlier, the director of a local health department said 11 wounded people had been taken to hospital.

“An explosion rocked the area and right after that children and people started running away,” said Ghulam Nabi, who was nearby when the bomb exploded. “I saw a vehicle catch fire and then a gunfight started.”

There are several other aid groups and government offices in the immediate area, and security forces evacuated people from surrounding buildings while they exchanged fire with the militants.

“We are devastated at the news that our Save the Children office in Jalalabad city, Afghanistan, came under attack this morning as armed men entered the building, about 9am today local time,” a Save the Children spokesperson said in a statement.

There was no immediate claim of responsibility but the Taliban issued a statement denying involvement.

Jalalabad, near the border with Pakistan, is often the target of militant attacks and is a strong base for the self-proclaimed Islamic State group.

Afghan forces, backed by US air strikes, have claimed growing success against militant groups, but attacks on civilian targets have continued, causing heavy casualties.

The attack in Jalalabad comes days after Taliban militants attacked the Hotel Intercontinental in the capital Kabul, killing at least 20 people including 13 foreigners.