MOSCOW, June 23 (Reuters) - Abu Dhabi state investor Mubadala has bought a 2.6% stake in Russia's En+ Group , which owns 56.9% in aluminium producer Rusal , Mubadala and En+ said on Wednesday.

Mubadala bought the stake from Polina Yumasheva, En+ said, the former wife of U.S.-sanctioned Russian businessman Oleg Deripaska.

Deripaska is a founder of Rusal and En+.

En+ "is a market leader in the clean energy and aluminium sectors, and is a welcome addition to Mubadala's growing and successful portfolio in Russia," Faris Sohail Al Mazrui, head of Mubadala in Russia, said in a statement.

Mubadala has a stake in Emirates Global Aluminium, which operates aluminium smelters in Abu Dhabi and Dubai.

Yumasheva's stake in En+ fell to 2.58% after the deal, and En+'s free float rose to 12.3%.

The U.S. Office of Foreign Assets Control (OFAC) has been notified of the sale, En+ added. (Reporting by Andrey Ostroukh in Moscow Writing by Polina Devitt Editing by Jan Harvey and Matthew Lewis)