A top provincial security official said Friday that the suicide attack on Benazir Bhutto bore the hallmarks of an Al Qaeda-linked, pro-Taliban warlord based near the Afghan border.

President Gen. Pervez Musharraf labeled the attack part of a "conspiracy against democracy," reaching out to the former prime minister with whom he is trying to forge a pro-U.S., anti-militant alliance.

The "signature at the blast site and the modus operandi" suggested the involvement of militants linked to warlord Baitullah Mehsud and Al Qaeda, said Ghulam Muhammad Mohtarem, the head security official in the province where Mehsud is based.

"We were already fearing a strike from Mehsud and his local affiliates and this were conveyed to the (Bhutto's Pakistan's) People's Party but they got carried away by political exigencies instead of taking our concern seriously," Mohtarem said.

There was no claim of responsibility for the bombing of Bhutto's convoy, which killed up to 136 people as she triumphantly paraded through her hometown of Karachi Thursday.

On the eve of her return from eight years in self-imposed exile, a provincial government official had cited intelligence reports that three suicide bombers linked to Mehsud were in Karachi. The local government had also warned Bhutto could be targeted by Taliban or Al Qaeda.

Local media reports this month quoted Mehsud — probably the most prominent leader of Islamic militants destabilizing its northwestern border regions near Afghanistan — as vowing to meet Bhutto's return to Pakistan with suicide attacks.

It remained unclear if the attack would stiffen Bhutto and Musharraf's resolve to fight militancy together or strain the already bad relations between Bhutto and the ruling party supporting Musharraf.

Bhutto's husband said on Dawn News television that he suspected "elements sitting within the government," who would lose out if Bhutto returned to power, were involved in the bombing.

He didn't elaborate, though Bhutto has accused conservatives in the ruling Pakistan Muslim League-Q party and the security services of secretly supporting religious extremists. Bhutto has made enemies of Islamic militants by taking a pro-U.S. line and negotiating a possible alliance with Musharraf, who is detested by militants for his alliance with the Bush administration.

Musharraf and Bhutto have been longtime rivals despite their shared liberal values, but his camp said he was "deeply shocked" by the midnight explosions, which went off near the armored truck carrying Bhutto, tearing victims apart and throwing a fireball into the night sky.

Officials at six hospitals in Karachi reported 136 dead and around 250 wounded, making it one of the deadliest bombings in Pakistan's history. Karachi police chief Azhar Farooqi said that 113 people died, including 20 policemen, and that 300 people were wounded. It was not immediately possible to reconcile the death tolls.

The attack shattered the windows of the truck but police said Bhutto was unhurt and was hurried to her house. An Associated Press photo showed a dazed-looking Bhutto being helped away from the scene.

The general "condemned this attack in the strongest possible words. He said this was a conspiracy against democracy," the state-run Associated Press of Pakistan said.

Musharraf appealed for calm, promised an exhaustive investigation and stiff punishment for those responsible, APP reported.

Presidential spokesman Rashid Qureshi said he doubted the attack would deflect Bhutto from her move toward an alliance with Musharraf, who seized power in a coup and has been under growing pressure to return Pakistan to a more democratic system.

"If someone thinks that by spreading this kind of terror they will stop the political process in Pakistan, I don't think that's correct, I don't think that will happen," Qureshi told The AP.

Musharraf won re-election to the presidency in a vote by lawmakers this month that is being challenged in the Supreme Court. If he is confirmed for a new five-year presidential term, Musharraf has promised to quit the military and restore civilian rule.

Musharraf believes that "all political forces need to combine to face this (militant) threat which is basically the major, major issue that faces Pakistan," Qureshi said.

Leaders of Bhutto's Pakistan People's Party were meeting at her Karachi residence Friday, and Bhutto was expected to hold a news conference afterward.

Police were collecting forensic evidence — picking up pieces of flesh and discarded shoes — from the site of the bombing. The truck was hoisted away using a crane. One side of the truck, including a big portrait of the former premier was splattered with blood and riddled with shrapnel holes.

Interior Minister Aftab Khan Sherpao said 18 police died in the attack, and two police vehicles on the left side of Bhutto's truck had borne the brunt of the blast.

He said authorities had done everything possible to protect the huge gathering, but noted that electronic jammers fitted to the police escort vehicles were ineffective against a manually detonated bomb.

In Karachi, which lies in the far south of Pakistan but has been buffeted by militant attacks in recent years, schools were closed and traffic was thin, with residents wary of venturing into the streets.

Unrest broke in two districts but did not appear serious. Hundreds of Bhutto supporters hurled stones at vehicles and shops during a funeral procession for two victims, forcing police to cordon off the area. Elsewhere, Bhutto supporters ordered shops to close and burned tires in the road.

Bhutto had paved her route back to Pakistan through negotiations with Musharraf that yielded an amnesty covering the corruption charges that made Bhutto leave Pakistan.

Authorities had warned Bhutto that extremists sympathetic to the Taliban and al-Qaida could target her in Karachi and urged her in vain to use a helicopter to reduce the risk.

"I am not scared. I am thinking of my mission," she had told reporters on the plane from Dubai.

On arrival, she told AP Television News she was fighting for democracy and to help this nuclear-armed country of 160 million people defeat the extremism that gave it the reputation as a hotbed of international terrorism.

"That's not the real image of Pakistan," she said.

Leaving the airport, Bhutto refused to use the bulletproof glass cubicle that had been built atop the truck taking her toward the tomb of Pakistan's founding father, Mohammed Ali Jinnah. An AP photographer who saw the cubicle of the wrecked truck Friday said it appeared to have shrapnel holes from the bombing.

Her procession had been creeping toward the center of Karachi for 10 hours, as supporters thronged her truck, when a small explosion erupted near the front of the vehicle.

That was quickly followed by a larger blast, destroying two escorting police vans.

The former premier had just gone to a downstairs compartment in the truck for a rest when the blast occurred, said Christina Lamb, Bhutto's biographer.

"So she wasn't on top in the open like rest of us, so that just saved her," Lamb told Sky News.

The United States, the United Nations and the European Union condemned the attack.

"Extremists will not be allowed to stop Pakistanis from selecting their representatives through an open and democratic process," said Gordon Johndroe, President Bush's foreign affairs spokesman.