Investigators on Sunday attempted to identify a suicide bomber who tried to kill Pakistan's interior minister in what officials suspect may have been attack planned by Islamist militants.
At least 26 people were killed and dozens hurt when a man blew himself up on Saturday just three metres from the Interior Minister Aftab Ahmed Khan Sherpao in North West Frontier province bordering Afghanistan.
Sherpao, who was meeting people at the end of public meeting in Charsadda, sustained minor leg injuries from shrapnel and pellets.
Investigators found the severed head and torso of the grey-bearded suspect and were trying to establish his identity.
"It is a continuation of what is going on in our tribal areas and across the border in Afghanistan," Asif Iqbal Daudzai, Information Minister for the North West Frontier Province (NWFP) told.
A senior police investigator said the bomber appeared to be in his 30s. "He is either an Afghan or belongs to our tribal areas," he said.
"The pattern of attack was similar to previous ones, all of which had links in our tribal areas," he added.
Pakistan has been plagued by bomb attacks by Islamist militants following President Pervez Musharraf's decision in 2001 to join a US-led war on terrorism. There were a spate of suicide attacks earlier this year, including one in the capital, Islamabad.
Sherpao said he was target of the attack.
Afghan President Hamid Karzai, a fellow ethnic Pashtun, telephoned Sherpao soon after the attack to ask how he was.
One of Sherpao's aides and several of his security detail were killed.
Doctors in Charsadda and nearby Peshawar, capital of NWFP, said scores of people were wounded and several were in a critical condition.
In Washington, White House spokesman Tony Fratto said the attack "shows the terrorists are out there as we saw from this activity in Pakistan but also from the roundup in Saudi Arabia".
Saudi Arabia said on Friday it had thwarted a plot to attack oil facilities and other installations and 172 people had been arrested.
Earlier on Saturday, a small blast outside a cafeteria at Peshawar International Airport broke windows, but caused no casualties.
North West Frontier province is one of the most volatile regions of Pakistan.
Al-Qaeda and the Taliban have drawn support from the fiercely independent tribesmen of North West Frontier, particularly in North and South Waziristan, the poorest of Pakistan's seven semi-autonomous tribal regions.