ISLAMABAD, Pakistan -- A suicide bomber blew himself up yesterday before a rally supporting Pakistan's chief justice against the president, killing 15 people in the latest attack in a spate of violence since the army stormed a mosque held by Islamic extremists.
The bloodshed has heightened tensions, with religious radicals calling for more revenge attacks on the government and troops moving into militant strongholds on the border with Afghanistan, a move welcomed by Washington as help in the fight against terror groups.
The bombing in Islamabad underlined the antagonism as various parties sought to place blame.
President Pervez Musharraf condemned the blast as a "terrorist act," and officials said they were trying to determine responsibility. A security official said the bomber's severed head had been found.
Supporters of Judge Iftikhar Mohammed Chaudhry accused the government of being behind the mayhem, while an opposition party thought to be considering whether to join a coalition government with Musharraf after year-end elections said the attack was aimed at its loyalists.
Chaudhry, whose fight against Musharraf's effort to oust him has fueled opposition to the president extending his rule, was a few miles away when the attacker struck about 8:30 p.m. outside the Islamabad district court building.
The judge arrived a short time later, and police ushered him into a tent set up for a rally by lawyers who have led frequent protests against his suspension. Chaudhry spoke briefly with the lawyers, who said he offered prayers for the victims, then canceled his speech and left.
Kamal Shah, a top Interior Ministry official, said the explosion killed 15 people and wounded 44. Opposition party activists, police officers, and bystanders were believed to be among the victims.
Three security officials, speaking on the condition of anonymity because they were not authorized to speak on the record, called it a suicide attack .
The bomb went off next to stalls set up by Pakistan's two main opposition parties, led by exiled former prime ministers Benazir Bhutto and Nawaz Sharif.
Shah said it was too early to "raise a finger at someone" in connection with the attack.
One of Chaudhry's lawyers, Munir Malik, accused Pakistani intelligence agencies. "This was an attack on the chief justice," he said.
Raja Pervez Ashraf, a leader of Bhutto's Pakistan People's Party, said, however, that the attacker targeted her activists.
"Most among the dead and injured are our supporters," Ashraf said.
Musharraf ordered an immediate inquiry and appealed to the public "to remain calm, vigilant, and assist the authorities in unearthing the culprits and bringing them to justice."
Some analysts and diplomats expect Bhutto to team with Musharraf in a power-sharing government after elections this year. She was the only opposition leader to voice strong support for a crackdown on the Red Mosque, which caused more than 100 deaths in eight days of fighting.
Taliban and Al Qaeda leaders and other militants have called for attacks to avenge the mosque's defenders, and a suicide blast killed three soldiers in the volatile North Waziristan region yesterday . Bombings and suicide attacks have killed more than 100 people in the northwest since the mosque battle.
Government officials continued their effort to salvage a 10-month-old peace accord in North Waziristan, a hotbed of Taliban and Al Qaeda militancy on the Afghan frontier where some leaders renounced the accord after the Red Mosque fighting.
Musharraf argues it is important to retain the accord, which saw the army scale back military operations in return for pledges from tribal elders to expel foreign fighters and prevent attacks on US troops in Afghanistan.
Washington pledged $750 million over five years to help the impoverished region and to dry up support for Islamic extremism as part of the accord. But US officials are pressing for more military strikes on extremists.
"Now, having dealt with the mosque, it's pretty much crossing a line, and there's no going back," Assistant Secretary of State Richard Boucher said yesterday.
While a civilian "hearts and minds campaign" may offer the best long-term solution to combating militants in the region, "some elements have to be dealt with militarily," he said.