Aitzaz, who was arrested on Friday from Dera Ismail Khan, revealed that he had been asked to attack Benazir in Karachi in the event of her escaping the attack in Rawalpindi, the newspaper Dawn quoted sources as saying.
After Bhutto's assassination, Aitzaz was directed to move to Karachi to target the US Consulate, the sources said.
Aitzaz claimed that he had received terrorist training along with two suspects Bilal and Ikram, whose names had been mentioned in the transcript of a telephone conversation, intercepted after the assassination of the former PPP leader in Rawalpindi on December 27.
Police raided an under-construction house of Sher Zaman, an accomplice of Aitzaz, in Tariqabad area of Dera Ismail Khan city and seized explosives and other material used in suicide vests.
Aitzaz and Sher Zaman were taken to Islamabad on Sunday night for further interrogation.
Meanwhile, Aitzaz's uncle Shabbir Hussain Shah had also been arrested in a raid at his Mansehra residence in the North Western Frontier Province.
During interrogation, Shabbir Shah claimed that Aitzaz's family had been living in Karachi for several years, and he had been missing for the last one year.