Authorities arrested two more suspects Thursday in the suicide attack that killed Pakistan opposition leader Benazir Bhutto, an official said. Interior Ministry spokesman Javed Iqbal Cheema said the two men were arrested in Rawalpindi, where Bhutto died in a gun and bomb attack on Dec. 27. He identified them only by the single names Rafaqat and Husnain, and provided no details of their alleged role in the attack that also killed 20 other people. Last month, authorities in northwestern Pakistan said they had arrested two suspects, including a 15-year-old boy who was alleged to have been part of the suicide squad assigned to kill Bhutto. The boy told investigators that the five-person squad had been dispatched to Rawalpindi by Baitullah Mehsud, a prominent Pakistani Taliban militant leader with strong ties to al-Qaida. The government had already accused Mehsud of orchestrating the attack. Thursday's arrests were disclosed hours after a team of Scotland Yard investigators returned to Pakistan to report the conclusions of their probe into the former prime minister's killing. The British investigators were assigned to resolve exactly how Bhutto died - amid confusion over whether she was killed by a gunshot or the impact of the suicide bombing that followed. Aidan Liddle, spokesman for the British High Commission, said it would release a summary of the report on Friday.