At least 26 people, including 13 police, were killed Sunday in a blast at a police recruitment centre in North West Frontier Province, an official said.

Hours earlier two explosives-packed cars ploughed into an army convoy in the province's Swat Valley, claiming 17 lives.

The previous day, a suicide car bomber killed 24 people in a similar attack on a paramilitary convoy in North Waziristan tribal region, launching the string of attacks that has also left scores wounded.

The death toll was expected to rise further after the latest blast, which left limbs and blood scattered across the police recruitment centre, with at least another dozen people in critical condition in a local hospital.

The bloodshed came amid outrage among hardliners in the mainly Muslim nation over the army's raid last week on Islamabad's Red Mosque, which has saddled President Pervez Musharraf with the worst crisis since he took power in 1999.

The raid which left 86 dead, most of them militants, led al-Qaeda's number two to call for jihad against the government, which has sent thousands of troops into remote tribal areas to try to keep a lid on bubbling public anger.

Interior Minister Aftab Sherpao said that while Saturday's attack in North Waziristan likely stemmed from an older dispute with tribal groups, he conceded that the other two attacks "to some extent ... could have some linkage with the Red Mosque."

Pro-Taliban militants in North Waziristan Sunday scrapped a controversial peace accord reached with the government last year, in which the tribal groups had promised to hunt down foreign fighters in return for security assurances.

The Taliban Shura (Taliban Council) said in pamphlets that it would refuse all dialogue and cooperation with authorities after the government had failed to meet a Sunday deadline to abandon 25 new military checkpoints.

"We had signed the agreement for the safety and protection of the lives and property of our people," the statement said. "But the government forces continued to launch attacks on the Taliban and have killed a number of people."

Sherpao, speaking on local television, countered: "We have been insisting that they are not enforcing the agreement strictly. Now the government will be justified if it takes some action."

Residents of Miranshah, the capital of North Waziristan, said about 100 local families had left, fearing clashes, and that the main bazaar was deserted, while families of many government employees had also fled.

Pakistani army trucks carrying thousands of additional troops have rumbled into remote areas in recent days after Musharraf vowed to crush extremists and "root them out from every corner of the country."

The United States has raised pressure on ally Musharraf, the army chief who grabbed power in a coup eight years ago, to do more to hunt down Taliban and al-Qaeda insurgents hiding in Pakistan's rugged lands bordering Afghanistan.

New US intelligence reports suggest al-Qaeda is gaining strength and has established a safe haven in remote tribal areas of western Pakistan for training and plotting new attacks, the Washington Post said last week.

The US administration Sunday lent its "full support" to Musharraf after the militants scrapped the peace accord with his government.

National Security Adviser Stephen Hadley, speaking on Fox News, said the deal "hasn't worked" in dealing with Taliban and al-Qaeda extremists.

"President Musharraf understands it," he said. "We understand it. President Musharraf is taking steps to move troops back into that region."

Besides the spate of violent attacks on government forces, there has been political fallout in the world's second-largest Muslim nation amid heightened tensions triggered by the week-long siege and final raid on the Red Mosque.

Qazi Hussain Ahmed -- the powerful head of the six-party Islamic alliance, the Muttahida Majlis-i-Amal -- said Saturday he would resign from parliament to protest the raid and the ongoing troop build-up.