Police had arrested Adil Azeem Sheikh and found a Kalashnikov and two grenades in his possession, SSP Munir Ahmed Sheikh told a news conference yesterday.
Sheikh was described as the "right hand" of Talat Hussain, the "supervisor" of Al Qaeda's chapter in Sindh and Balochistan provinces. He brought explosives from Balochistan and provided them to terrorists in Karachi, Sheikh said.
Media reports quoted official sources as saying that Sheikh confessed during interrogation that he was part of the team that planned the attack on the Inter-Services Intelligence's regional office at Sukkur for releasing two associates detained by the agency.
Sheikh said two other members of his group had abetted the plot. He also reportedly told interrogators that Talat Hussain had asked him to bomb the homecoming caravan of slain former premier Benazir Bhutto in Karachi in 2007 but he refused to do so.
Police claimed that Sheikh was trained in the Afghan province of Kunar.