Headley was a Pak spy working for ISI

"In essence, US and Indian officials say, Headley was more than a terrorist: He served as a Pakistani spy," investigative American journalist Sebastian Rotella wrote in `ProPublica.Com`.

Investigation into the Mumbai terrorist attacks by the US and Indian agencies, the news report said, has for the first time given a detailed account of how Pakistan`s powerful ISI has been playing the "double game": acting as a front-line US ally in the fight against terror while supporting selected terrorist groups which serve Pakistani interests.

Documents about Mumbai attacks investigation in possession with ProPublica.Com, have built a strong case that officers in Pakistan`s Inter-Services Intelligence (ISI) Directorate collaborated with the Lashkar-e-Taiba terrorist group in the plot that killed 166 people, six of them Americans, Sebastian wrote.

"Officials from both countries (India and the US) say they are persuaded that ISI officers recruited and trained Headley in spying techniques and gave him money and instructions to scout targets in Mumbai and elsewhere.

"Headley has told investigators that a Pakistani navy frogman helped plan the maritime attack on Mumbai," the news report said citing a 119-page report recounting his interrogation this year by Indian authorities.

The report, which was obtained by ProPublica, quoted Headley as saying his Pakistani intelligence handler took part in a discussion about a subsequent Lashkar plot to attack a Danish newspaper -- information that Pakistan did not share with Danish authorities, it said.

While the allegations have been denied by Pakistani authorities, according to ProPublica, US investigators see much of Headley`s account as credible.

In a potentially significant revelation, ProPublica reports that Headley said Lt Gen Pasha, the director general of the ISI, went to see Zakiur Rehman Lakhvi, the LeT military chief, in custody after he was arrested post-26/11.

"Pasha had visited him to understand the Mumbai attack conspiracy," the report quoted Headley as saying, without further elaboration.

"Pakistani officials deny that the spymaster made the jailhouse visit. US and Indian officials and experts are more willing to believe the story," it said.