Ansari has also told investigators he fled India in 2006 across the border to Bangladesh, escaping from a police raid in Aurangabad on an illegal cache of weapons and explosives intended for future attacks within India, the officials said.
Ansari then moved to Pakistan, trained with Lashkar and joined in planning future attacks, officials said, speaking on condition of anonymity because of the sensitivity of the case.
Pakistan insists that the ISI has no links to Lashkar, and denies any connection to the Mumbai attacks.
The assault was like no other India had experienced. Bombs and grenades went off at the famed Taj and Trident hotels. Then, 10 trained Pakistani militants fanned out through the hotels and through the main train station and a Jewish cultural center and gunned down people in their paths.
The attack went on for three days, as Indian police scrambled to keep up with the militants who were receiving detailed instructions by cell phone.
Image: In this Nov. 29, 2008 file photo, an Indian soldier takes cover as the Taj hotel burns during a gun battle between Indian military and militants inside the hotel in Mumbai.