Security agencies in Pakistan's North West Frontier Province have arrested a teenaged boy on suspicion of involvement in the assassination of former premier Benazir Bhutto.

Aitezaz Shah, 15, was arrested on Thursday in Dera Ismail Khan town in the NWFP, 280 km southwest of Islamabad, security sources told Al Jazeera on Saturday.

Shah, who hails from Karachi, told investigators that he was part of a squad of five suicide bombers sent by Tehrik-e-Taliban Pakistan chief Baitullah Mehsud to assassinate Bhutto in Rawalpindi, the sources said.

Shah said two of the attackers, Akram and Bilal, were to target Bhutto first. If they failed, the other three were to carry out the operation.

He said Bilal killed Bhutto by shooting her and detonating an explosive vest as she was leaving an election rally on December 27. The blast killed nearly 30 others and wounded dozens more.

The whereabouts of the two other members of the suicide squad are unknown, the sources said. Shah returned to the NWFP after the operation against Bhutto and was assigned to carry out a suicide attack on an unspecified foreign consulate in Karachi, Al Jazeera reported.

However, interior ministry spokesman Jawed Iqbal Cheema said he had no information about any arrests in Dera Ismail Khan or of any new development in the probe into Bhutto's assassination.

Baitullah Mehsud, a pro-Taliban leader from the South Waziristan tribal region, who has strong links to Al Qaeda [Images], was blamed by president Pervez Musharraf [Images] for masterminding Bhutto's assassination and other suicide attacks across Pakistan.

US' Central Investigation Agency director Michael Hayden too has said that Bhutto was killed by fighters allied to Baitullah Mehsud with support from Al Qaeda's terrorist network. "This was done by that network around Baitullah Mehsud. We have no reason to question that," he said.

Baitullah Mehsud has denied involvement in Bhutto's killing.

Shah said he had gone for training in 2007 to a camp run by one of Mehsud's commanders in Waziristan, the sources said.

Significantly, the names of the alleged attackers given by Shah - Bilal and Akram - match the names of the men mentioned in a phone conversation between Mehsud and another militant the day after Bhutto's assassination.

When Mehsud asked who had carried out the attack, the other militant replied, "There was Saeed, the second was Badarwala Bilal and Ikramullah was also there".

Bhutto had returned to Pakistan in October 2007 after nearly eight years in exile following secret parleys with Musharraf. Her assassination sparked violent protests across Pakistan that left over 50 people dead and damaged property worth billions of rupees. The violence forced the Election Commission to delay parliamentary polls by six weeks.