Browne has been appointed as chairman of DEA, the oil and gas unit that German utility RWE has sold to Russian billionaire Mikhail Fridman's LetterOne investment firm.

Riverstone said on Tuesday Browne was not standing for re-election to the board at its annual general meeting on May 13.

The investment firm said it was proposing Rothschild Bank's Claire Whittet for election to the board at the meeting.

(Reporting by Karolin Schaps; Editing by Mark Potter)