At least six people have been killed in an attack by a suicide bomber in northwest Pakistan, officials have said.

The bombing occurred in Kabal district in the restive Swat valley region on Sunday, where Pakistan's military has battled fighters loyal to Maulana Fazlullah, an Islamic leader loyal to the Taliban.

"It was a suicide attack. The bomber hit the checkpost barricades with the car and then blew himself up," Amjad Iqbal, a provincial government spokesman, said.

"Two children, three civilians and a policeman were killed. One policeman was wounded," he said.

Military offensive

The bombing comes a day after officials said they had almost cleared Swat valley, which lies 160km from Islamabad, of opposition fighters.

Major General Nasser Janjua said his troops had killed 290 fighters, who he said were supported by the Taliban and al Qaeda.

A further 143 were captured in the offensive involving 20,000 troops, he said.

In a separate incident on Sunday, suspected opposition fighters fired rockets at an air force base in the northwest city of Peshawar, capital of the North West Frontier Province.

Two rockets landed in a field at the base while a third rocket hit a road near the base after midnight, Mohammad Tahir Khan, a senior police official, said.

Part of the base is used for domestic and international passenger flights.

A girls' school was also bombed in the city, but police said there were no casualties in the attack.

Peshawar is located close to Pakistan's semi-autonomous tribal areas, where government forces are fighting Taliban and al-Qaeda loyalists.

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