Dia shared the news on Twitter, saying she is happy to be on board for the project.
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She posted: "The happiest place in the world is on a Rajkumar Hirani film set. Sanjay Dutt biopic, Ranbir Kapoor, Vicky Kaushal."
Ranbir, who was last seen on the big screen in filmmaker Karan Johar's multi-starrer "Ae Dil Hai Mushkil", will essay the role of Sanjay in the upcoming biopic.
Dia also shared an image of the cast cutting a cake together on the set.
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Earlier, Hirani had shared that the first shot for the biopic has been taken and there is excitement among the film's team. He had tweeted on Saturday: "First shot taken now for Sanjay Dutt's biopic. Canning a very funny scene. Excitement in cast and crew."
IANS