The makers of superstar Rajinikanth's Tamil film "Kaala" haven't reacted to rumours about Malayalam megastar Mammootty being part of the project, which is being directed by Pa. Ranjith and produced by Dhanush.Social media is buzzing with reports that Mammootty has been signed on to play B.R. Ambedkar-like role in the film.Reacting to the reports, a source from the film's unit told IANS: "I'm not at liberty to speak. It's best if the makers react to such things."In the film, Rajinikanth plays a slum-lord-turned-gangster.Huma Qureshi, Nana Patekar, Anjali Patil, Samuthirakani and Pankaj Tripathi play key roles.The project marks the reunion of Ranjith and Rajinikanth, who had previously worked together in "Kabali".Meanwhile, several shooting stills have been leaking from the sets of the film on a daily basis. The makers are finding it extremely difficult to control the leak."We are currently shooting in Mumbai, and most of it is happening outdoors. With Rajini sir on sets, it's extremely difficult to stop people from taking pictures. Thanks to technology, great pictures are taken even while standing hundreds of metres away," the source said.The film has music by Santhosh Narayanan.