The BBC's Harun Najafizadah says staff were being kept in a safe room in a bunker. Photo: BBC NEWS

Gunmen have entered a nearby building and are firing at the election commission with automatic weapons.

Afghan special forces have entered the building to confront the attackers, police say.

The attack comes a week before presidential elections which the Taliban have vowed to disrupt.

It comes a day after a major onslaught on a building housing foreign aid workers in the Afghan capital.

Taliban spokesperson Dr Zabiullah Mujahid has confirmed to the BBC that the militant group was behind the attack.

The assailants are using a three-storey building as a launching pad to attack the heavily secured compound of the Independent Election Commission (IEC), a senior official told the BBC.

He said several warehouses in the compound have come under fire, including one containing election materials for Kabul province.

Separately, Kabul police chief General Zahir told the BBC they had "cornered the attackers" and that elite forces were confronting the insurgents inside the building.

He said that there were four attackers armed with rocket-propelled grenades and small and heavy weapons.

Security is a major issue both during and after the presidential elections scheduled for 5 April

The commission is on a specially built site on a main road out of the centre of Kabul to the east, says the BBC's David Loyn in Kabul. It is not yet clear if there are any casualties.

"We heard two explosions inside the IEC compound, the sound of firing is still ongoing, but people are safe and are in (reinforced) safe rooms," IEC spokesman Noor Mohammad Noor tells AFP news agency.

The group has threatened a campaign of violence to disrupt the polls on 5 April, urging their fighters to attack polling staff, voters and security forces in the run-up to election day.

The latest attack comes hours before the election commission was due to announce details of how many polling stations will be opened.

It is the second attack against an IEC office in the Afghan capital this week.

Recent Taliban attacks include:

• 28 March: Gunmen trap several people inside guest house housing foreign aid workers in Kabul. Officials say they killed a 10-year-old girl playing outside in the street
• 25 March: Taliban suicide bomber strikes IEC office in Kabul, killing two policemen
• 20 March: 18 policemen killed in attack in eastern Afghanistan. Nine killed, including four foreign nationals, in separate attack on an upmarket hotel in Kabul