Pakistan's spy agency ISI helped terror group Lashkar-e-Taiba to execute the Mumbai terror attacks, David Coleman Headley, a key 26/11 accused who pleaded guilty to laying the groundwork for the 2008 strikes, told a court here today.

The testimony by 50-year-old Headley, a prosecution witness, came as the trial of Mumbai attacks co-accused and his longtime friend Tahawwur Rana, a Canadian of Pakistani origin, opened in the US at Chicago's Dirksen Federal Building. Pakistani-American Headley is also a co-accused.

Headley had scouted India's key atomic installation BARC and had visited Shiv Sena headquarters in Mumbai, said prosecutor Sarah Streicker told Judge Harry D Leinenweber.

Headley had gone to Shiv Sena office to build contacts with its public relations officer Rajaram Rege.

In his statements, Headley said ISI provided help to LeT and that he first started training in Pakistan more than a decade ago with the Lashkar.

Headley said LeT chief Hafiz Saeed, the mastermind behind the 26/11 attacks that killed 166 people, motivated him for carrying out a "jihad".

Saeed told him that the satisfaction of one second of "jihad" is equal to "100 years of worship."

LeT operators also chose Headley because he was an American and that people would least suspect him. He also mentioned that Hafiz Saeed and others like Major Abdur Rehman Pasha, Major Iqbal, Zaki Saab, Sajid Mir helped him.

Streicker said that Rana knew all along what Headley was doing with the preparation of the attacks and that "India deserved it". .

"Rana knew all along what Headley was doing and defendant moved his business for Headley's terror and plotting of attacks," Streicker told the court.

"Defendant Rana knew about the deadly consequences of his assistance and he did not stop to provide assistance," Streicker added.

On the other hand, Rana's lawyer Charlie Swift, who has defended the case of Osama bin Laden's driver Salim Ahmed Hamdan, said that Headley was "manipulative leading multi-lives" and maintained three wives.

Swift also played a telephonic call between Abdur Rehman Pasha and Headley in which he made fun of Rana. Swift said that Headley was a double agent who worked for ISI and CIA, DEA at the same time.

Rana bailed Headley by putting his house when he got busted for drugs in 1990. He pleaded guilty in an act of "cleansing of his soul" and thus duped Rana, his best friend from a prestigious military college Abdal Hasan. While Rana was a model cadet, Headley was the "bad boy", who did not graduate, his lawyer said.

Rana served in Gulf War with coalition and later went to Germany. He later immigrated to Canada and moved to Chicago to start businesses.

"David Headley is a master manipulator who made a fool of Rana," Swift said.

A bald Headley, wearing a blue T-shirt and black jacket, admitted that Rana had helped him conduct the role in the carnage that killed 166 people including six Americans.

"I disliked India when I was in Pakistan and after my school was bombed in 1971," he said. Headley also said that he did not like Pak-Kashmir dispute and was wanting to get launched in Kashmir but was told to wait for a more suitable job. At the time of the conspiracy Rana owed a debt of USD 50,000 to Headley from a 2001 debt. .