( AP ) - An Islamic militant group said Saturday it had no link to Benazir Bhutto's killing, dismissing government claims that its leader orchestrated the assassination.
Bhutto's aides also said they doubted militant commander Baitullah Mehsud was behind the attack on the opposition leader and accused the government of a cover-up.
The dispute and conflicting reports about Bhutto's exact cause of death were expected to further enflame the violence wracking this nuclear-armed nation two days after the popular former prime minister was killed in a suicide attack.
Roads across Bhutto's southern Sindh province were littered with burning vehicles as mobs of supporters continued their rampage. Factories, stores and restaurants were set ablaze in the city of Karachi, where 17 people have been killed and dozens injured, officials said.
Army, police and paramilitary troops patrolled the nearly deserted streets of Bhutto's home city of Larkana, where rioting left shops at a jewelry market smoldering.
Former Prime Minister Nawaz Sharif led a 47-member delegation of other opposition leaders to meet with Bhutto's family to express condolences, said Sadiq ul-Farooq, spokesman for Sharif's party.
President Pervez Musharraf called Bhutto's husband, Asif Ali Zardari, promising to make every effort to bring the attackers to justice, state-run Pakistan Television reported.
The government blamed Bhutto's killing on al-Qaida and Taliban militants operating with increasing impunity in the lawless tribal areas along the border with Afghanistan. It released a transcript Friday of a purported conversation between Mehsud and another militant, apparently discussing the assassination.
"It was a spectacular job. They were very brave boys who killed her," Mehsud said, according to the transcript.
Interior Ministry spokesman Javed Iqbal Cheema described Mehsud as an al-Qaida leader who was also behind the Karachi bomb blast in October against Bhutto that killed more than 140 people.
But a spokesman for Mehsud, Maulana Mohammed Umer, denied the militant was involved in the attack and dismissed the allegations as "government propaganda."
"We strongly deny it. Baitullah Mehsud is not involved in the killing of Benazir Bhutto," he said in a telephone call he made to The Associated Press from the tribal region of South Waziristan.
"The fact is that we are only against America, and we don't consider political leaders of Pakistan our enemy," he said, adding that he was speaking on instructions from Mehsud.
Mehsud heads Tehrik-i-Taliban, a newly formed coalition of Islamic militants committed to waging holy war against the government, which is a key U.S. ally in its war on terror.
Bhutto's Pakistan Peoples Party accused the government of trying to frame Mehsud, saying the militant - through emissaries - had previously told Bhutto he was not involved in the Karachi bombing.
"The story that al-Qaida or Baitullah Mehsud did it appears to us to be a planted story, an incorrect story, because they want to divert the attention," said Farhatullah Babar, a spokesman for Bhutto's party.
After the Karachi attack, Bhutto accused elements in the ruling pro-Musharraf party of plotting to kill her. The government denied the claims. Babar said Bhutto's allegations were never investigated.
Bhutto was killed Thursday evening when a suicide attacker shot at her and then blew himself up as she left a rally in the garrison city of Rawalpindi near Islamabad. The attack killed about 20 others as well. Authorities initially said she died from bullet wounds, and a surgeon who treated her said the impact from shrapnel on her skull killed her.
But Cheema said she was killed when she tried to duck back into the armored vehicle during the attack, and the shock waves from the blast smashed her head into a lever attached to the sunroof, fracturing her skull,