Bomber killed in Pakistan blast 

A suicide bomber set off explosives in the car park at the airport of the Pakistani capital Islamabad on Tuesday after being challenged by police and three people were wounded, officials said.

It was the second suicide bombing in Islamabad since January 26 and is bound to raise fears Pakistan's war against Islamist militants in remote mountains on the Afghan border has spread to the relatively peaceful capital.

The bomber was stopped in a car just outside the airport and ran into the airport's car park after police tried to search him. He opened fire at police chasing him before blowing himself up, police said.

"The suicide bomber was killed and two airport security people were wounded," Interior Minister Aftab Ahmed Khan Sherpao told Reuters.

Police said one policemen was also wounded when the bomber opened fire.

Two accomplices of the bomber were arrested, Sherpao said.

Police sealed off the airport soon after the blast but the remains of a body could be seen in the car park through a fence, a witness said.

"This is a pure act of terrorism," said retired Brigadier Javed Iqbal Cheema, head of an Interior Ministry crisis management section.

An aviation official said flights coming to and from Islamabad were expected to be delayed.

Militant link

Pakistan has seen several suicide attacks in recent days that have killed nearly 30 people.

A suicide bomber killed himself and a guard while trying to enter one of Islamabad's top hotels on Jan. 26 .

The wave of bombings followed a Pakistani military air strike on an Islamist militant camp in the South Waziristan region on the Afghan border in mid-January that killed up to 20 people.

Analysts have speculated the blasts have been revenge for the air strike and Pakistani intelligence officials have linked at least some of the bombs to pro-Taliban militants in Waziristan led by Baitulah Mehsud.

Many al Qaeda and Taliban members fled to Pakistan's semi-autonomous tribal lands from Afghanistan after US-led fores overthrew the Taliban in late 2001.

Pakistan, an important US ally in the war on terrorism, has been trying to clear foreign militants out of the area and pacify their Pakistani allies and hundreds of people have been killed in clashes.

But Islamabad - a small, leafy capital nestled against the foothills of the Himalayan mountains - had been largely free of militant violence in recent years.

Security in the city has been much tighter than usual in recent days with police stepping up patrols and checks on roads and at entrances to sensitive areas such as the diplomatic quarter.