The Pakistani police claimed to have seized a suicide jacket and explosives from the accomplice of a teenager who was arrested last week on suspicion of involvement in the assassination of former premier Benazir Bhutto [Images].

Police in Dera Ismail Khan town in North West Frontier Province described Sher Zaman, the accomplice of 15-year-old Aitezaz Shah, as the mastermind of a "big terrorist plot".

Zaman, a former political official of South Waziristan tribal agency, was arrested on the basis of information provided by Shah, police said. Zaman was living at Tariqabad in Dera Ismail Khan.

Police and security officials who raided Zaman's residence seized a jacket used in suicide attacks along with a switch and an electric detonator, four grenades and half a kg of explosives, police said on Monday.

Shah, who was also arrested in Dera Ismail Khan on Thursday, told police that he had come to the town from Karachi to meet Zaman for getting instructions and to collect materials used in suicide attacks.

These were the first arrests made in the probe into Bhutto's assassination.

Shah has told investigators he was trained as a suicide bomber and was part of a five-man squad sent by Tehrik-e-Taliban Pakistan commander Baitullah Mehsud to kill Bhutto.

Security personnel also raided Shah's home in Battal area of Mansehra district of NWFP on Sunday.

Pakistani officials have been tight-lipped about the arrest of the two suspects. Interior Secretary Syed Kamal Shah has only confirmed that two persons were arrested in Dera Ismail Khan and that one of them, a teenaged boy, had confessed to involvement in the attack on Bhutto.

Shah told investigators that 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 in Rawalpindi 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.

However, a spokesman of Baitullah Mehsud has denied that the Taliban commander had any links with Shah, saying that the teenager had not been tasked by the militant group to carry out any attacks.

Mehsud has also denied involvement in Bhutto's killing.