PARIS, March 12 (Reuters) - European private equity firm Charterhouse Capital Partners said on Friday it had entered exclusive talks to sell a majority stake in French drugmaker Cooperation Pharmaceutique Francaise, known as Cooper, to CVC Capital Partners.

The deal values the Paris-based firm at about 2.2 billion euros ($2.6 billion) and will see Charterhouse reinvesting in the business after having more than doubled its size since taking control in 2016, a source familiar with the matter told Reuters.

Following the deal and reinvestment, Charterhouse will own about 20% of the firm, the source said.

The London-based private equity firm is expected to return more than 1.2 billion euros to its investors when the deal completes, the source said.

Rothschild and HSBC advised Charterhouse on the transaction, while Freshfields Bruckhaus Deringer provided legal advice.

Cooper, which has approximately 850 full time employees, started as a pharmacists' cooperative outside Paris more than 100 years ago.

Charterhouse transformed the firm from a largely France-focused over-the-counter (OTC) distributor into an integrated manufacturing and distribution platform operating across several international markets, with deal-making playing a key role in its expansion.

"The company has built an excellent position in a growing, highly attractive market and we look forward to continuing to support its expansion," said Charterhouse's partner Vincent Pautet.

Under Charterhouse's ownership, Cooper grew its revenues from 215 million euros in 2016 to 496 million euros in 2020, while its earnings before interest, taxes, depreciation and amortization (EBITDA) jumped from 65 million euros to 155 million euros in the same period, the source said.

Key acquisitions included the 2016 purchase of Vemedia, which ranked as one of Europe's leading producers and distributors of OTC drugs, food supplements and medical devices.

Cooper also acquired a portfolio of 12 pharmaceutical brands from French drug giant Sanofi for 158 million euros in 2018.

($1 = 0.8391 euros) (Reporting by Dominique Vidalon and Pamela Barbaglia; Editing by Jason Neely and Jan Harvey)