In a joint operation, law enforcement agencies have arrested the alleged terrorist responsible for a 2007 bomb blast in former Pakistani Premier Benazir Bhutto's rally in the southern port city of Karachi, a spokesman of the Interior Ministry said Monday. The alleged main suspect Azmatullah of disbanded Tehrik-e-Taliban Pakistan (TTP) was held responsible for the suicide bomb blast that have killed over 145 and injured some 450 in October 2007 in a welcome rally on Bhutto's returning home from self exile in Dubai. Bhutto, the Pakistan People's Party (PPP) Chairperson, had survived the attack. The ruling PPP is celebrating Benazir Bhutto's 57th birthday on Monday nationwide. Bhutto was assassinated on Dec. 27, 2007 in an election campaign rally in the garrison city of Rawalpindi, adjacent to the capital Islamabad. She had been Pakistan's prime minister twice in 1988-1990 and 1993-1996.