Torrent Pharmaceuticals is in talks with private equity funds CVC Capital Partners and Bain Capital to raise up to $1.5 billion to bid for India's Cipla (CIPL.NS), according to three sources with direct knowledge of the matter.

Torrent and Blackstone are among those interested to acquire a stake in Cipla, India's third-biggest drugmaker by sales, in what could be the largest pharma deal in India ever.

Cipla's founding family is keen to sell their 33.4% holding entirely, sources say, and any bid will also trigger an open offer for another 26% stake, as per Indian regulations. That translates to a $6.75 - $7 billion deal, Bernstein estimated in an Aug. 30 report.

Torrent is likely to reach a decision to finalize its consortium financing partner in the next few days, said the first source.

Bain and Blackstone declined to comment while Cipla, Torrent and CVC did not respond to comments.