Gunmen dressed in Afghan police uniforms and wearing suicide vests have stormed a government compound, killing seven people and wounding 12 others.

The four attackers targeted the offices of governor Mohammad Ikhpolwak in Farah, which borders Iran and is considered a trouble spot for the decade-old Taliban insurgency.

Two of the attackers detonated their suicide vests and the other two were shot dead by police, said interior ministry spokesman Sediq Sediqqi.

The ministry blamed the attack on terrorists.

The Taliban frequently target government compounds in attacks carried out by multiple militants carrying suicide vests, rockets and machine-guns.

The assault underscores the major security challenges as Afghanistan heads to a NATO summit in Chicago on Sunday, with a demand for $4.1 billion a year to bankroll its security forces after Western troops pull out in 2014.

Farah is a volatile area where remnants of the Taliban, ousted from power in the 2001 United States-led invasion, are fighting to bring down the Western-backed government.

This month, the militia announced the start of its annual spring offensive, a campaign of bombings and attacks that picks up every year as the weather warms.

In mid-April, dozens of people were killed and injured when Taliban suicide attackers occupied construction sites in Kabul, including one at the heart of the diplomatic enclave, unleashing a battle with security forces that lasted about 19 hours.

Most of the 130,000 NATO forces based in Afghanistan, mostly from the US, are due to leave by the end of 2014 under a US-led exit plan. A smaller number of US troops, mostly advisers and special forces, are likely to stay on to support Afghan police and soldiers.

Earlier this month, Afghanistan and the United States signed a "strategic partnership" mapping relations between Kabul and Washington from 2014 to 2024.

Prime Minister Julia Gillard last month outlined the Government's plan for an early withdrawal of Australian troops from Afghanistan which could see the majority of Australian soldiers return by the end of 2013.

AFP