"He (Sanjay Dutt) is co-producing the film. The decision was taken recently. The work on the script is still going on," sources close to Dutt said.
The yet-to-be-titled film will see actor Ranbir Kapoor essaying the turbulent life of Dutt, 56.
According to sources, Dutt has been working hard to grow his production house and in the process, his wife Manyata has signed Prabhu Deva to direct a home production project.
'Munnabhai MBBS' director Rajkumar Hirani is writing the biopic with Abhijat Joshi.
Hirani had earlier said that he wants to tell Sanjay Dutt's story "with all his flaws".
Dutt, son of veteran actors Sunil Dutt and Nargis, has witnessed a life full of upheavals in both professional and personal fronts.