The 70-year-old actor, who was last seen in a cameo in Mani Ratnam's "Guru" 2007, could be seen as Salman Khan's mentor within the film.
"Roshan Seth has lately been doing little or no acting work, and by choice. Besides 'Guru', he has not done a single Hindi film in ages, and positively not a mainstream commercial film," said a source with reference to the project.
Kabir and Seth's association goes back a protracted way.
"Seth has done the voiceover for each single documentary that Kabir Khan has made. When Kabir turned feature film director with 'Kabul Express', he again went to Seth to do the voiceover," said the source.
"Now when there has been an acting role in 'Ek Tha Tiger' which Kabir felt only Seth could do justice to, there has been no way Seth could say no to the director," the source added.
Apparently most of Seth's scenes are with Salman.
"Salman and Seth, who belong to fully different schools of acting, hit off beautifully. The vibes will show on screen," the source added.
However, Kabir remained unavailable for comment.
