PESHAWAR, Pakistan - A suicide bomber killed 10 people at a security post in Pakistan on Monday as the army pressed on with an offensive against the Taliban in which the government said 700 militants had been killed.

The offensive in the Swat valley, 130 km (80 miles) northwest of Islamabad, is seen as a test of the government's resolve to get to grips with an intensifying Taliban insurgency and comes after the United States accused it of abdicating to the militants.

The fighting has sparked a civilian exodus from the former tourist valley, raising fears of a humanitarian crisis.

At lest 360,000 people have left their homes in recent days and in all about 500,000 are expected to flee. They join about 600,000 people displaced earlier from Swat and other areas because of fighting since August.

The bomber killed two paramilitary soldiers and eight civilians when he set off his explosives in a queue of cars at a checkpost on the outskirts of the main northwestern city of Peshawar, said a police spokesman, Fazal Naeem.

The target was the checkpost but he couldn't manage to reach the soldiers because of the queue, Naeem said.

There was no claim of responsibility but militants have unleashed a wave of bomb attacks over the past two years, many aimed at ending military operations against them.

The army launched a full-scale offensive in Swat, about 110 km (65 miles) northeast of Peshawar, on Thursday after a peace pact broke down and the government ordered troops to eliminate the militants.

Interior Ministry chief Rehman Malik told reporters 700 Taliban and 20 soldiers had been killed. The was no independent confirmation of that estimate of militant casualties which was higher than figures the military has been providing.

The operation will continue until the last Taliban is flushed out, Malik said. The operation is continuing successfully. Our strategy has succeeded.

We haven't given them a chance. They are on the run. They were not expecting such an offensive.

Aircraft attacked militant positions in the valley on Monday, while a curfew kept frightened civilians huddled in their homes, residents said by telephone. The army lifted the curfew for nine hours on Sunday to enable people to flee.

The offensive was launched while President Asif Ali Zardari, the widower of former prime minister Benazir Bhutto, was in Washington assuring a nervous United States that his government was not about to collapse and was committed to fighting militancy.

Action by nuclear-armed Pakistan against militants in its northwest is vital for U.S. efforts to defeat al Qaeda and stabilize Afghanistan.

Most political parties and many members of the public support the offensive. That could change, however, if the civilians displaced in what the government say is the country's largest-ever internal migration are seen to be suffering unduly or if many civilians are killed in the fighting.

Opposition leader and former prime minister Nawaz Sharif, who has sounded supportive of government action against the militants, visited a camp for the displaced and said it was everybody's responsibility to help.

It's a very unfortunate situation, Sharif told reporters.

The nation in no way approves the activities of those elements who are responsible for the displacement and migration of these people, he said.

The U.N. refugee agency said 360,000 people had registered with authorities after fleeing the latest surge in violence, with about 20,000 of them staying in camps.

That figure is rising, said Ariane Rummery, a spokeswoman for the U.N. High Commissioner for Refugees. We see people on the move and know that more are coming.

Pakistan