HERAT, Afghanistan - A suicide bomber disguised as a beggar blew himself up inside a government building in Afghanistan Saturday, killing a state prosecutor and five other people, a provincial governor said.

The bomber, who had explosives strapped to his body, had tried several offices in the building in the town of Zaranj on the southwestern border with Iran before entering that of the attorney, Nimroz province governor told AFP.

Once inside, he blew himself up, bringing down the whole single-storey building, Governor Ghulam Dastgir Azad said.

"We have recoverd so far six bodies," he said.

The dead were provincial attorney Anwar Shah Khan, who had worked on intelligence matters, his 20-year-old son, and his deputy and three civilians, Azad said.

"The whole building has collapsed. There might be more casualties," the governor said.

The bomber had been able to get past an outer security gate because guards had taken shelter from a sandstorm in the desert province, Azad said.

People were searching under the rubble for more victims, police said.

There was no immediate claim of responsibility for the attack.

There has been a wave of suicide blasts in Afghanistan in the past three years, most of them claimed by Taliban extremists who are waging an insurgency against the US-backed government in Kabul.

The Taliban were in government between 1996 and 2001 when they were ousted in an invasion led by the United States and supported by Afghan anti-Taliban factions.

They have regrouped to put up an insurgency that is said to have support from other extremist factions, including Al-Qaeda, and radical elements based across the border in Pakistan.

The Afghan government is supported by about 54,000 soldiers in a NATO-led force and a few thousand more in a separate US-led force as it fights to rebuild its security forces and fight back the extremists.

A top US commander working in Afghanistan, Major General Jeffrey Schloesser, said Friday he needs more troops to counter growing insurgent violence amid signs the rebels were preparing for a winter campaign for the first time.

"I do believe that the level of significant activities, maybe violence, will be higher than any previous winter since 2002," Schloesser said in a video teleconference to Washington from his base in eastern Afghanistan. - AFP/vm