Gossip mills are abuzz that Deepika Padukone will be a part of the film too.
"We have not finalized anyone. Only the script is complete apart from Ranbir on board. Only this much is finalized. Once Saala Khadoos releases on January 29, then I will work on it," Mr Hirani told reporters at an event.
Sanjay Dutt, sentenced to five-year imprisonment after he was convicted for possessing an illegal weapon, part of the cache meant to be used during the 1993 Mumbai serial blasts, will be out of the jail next month. (Also Read: The Truth About Kangana Ranaut Starring in Sanjay Dutt Biopic)
Apart from the Sanjay Dutt biopic, Mr Hirani is also working on the third installment of his superhit Munna Bhai series.
When asked about the status of Munna Bhai series, Mr Hirani said, "Not in touch with him (Sanjay Dutt) for long time, as I was busy with Saala Khadoos and its promotions. I have heard he will come out at the end of next month. Once he is out then we will take it ahead."