FILE PHOTO: Billionaire activist-investor Carl Icahn gives an interview on FOX Business Network's Neil Cavuto show in New York, U.S. on February 11, 2014. REUTERS/Brendan McDermid/File Photo

(Reuters) - Activist investor Carl Icahn on Friday added two more nominees to his slate for the board of SandRidge Energy Inc SD.N after the company expanded its board, suggesting that the hedge fund manager planned to press ahead with the proxy fight.

The U.S. shale oil producer said last week it would expand the board size to seven from five, to allow investors to pick two nominees from Icahn’s five-person slate.

Icahn, who holds a 13.51 percent stake in SandRidge, got the company to back out of its planned buyout of rival Bonanza Creek Energy Inc BCEI.N and forced the removal of the company's chief executive and chief finance officer.

The billionaire investor on Friday nominated Jonathan Christodoro, a former managing director of Icahn Capital LP, and Nancy Dunlap, the private counsel and head of the private family office of former U.S. Senator Jon Corzine.