June 21 (Reuters) -

Activist investor Elliott Investment Management is increasing pressure on NRG Energy and seeking to oust its CEO Mauricio Gutierrez, the Wall Street Journal reported on Wednesday, citing people familiar with the matter.

Elliott is in talks with potential candidates to replace the U.S. power company's CEO as well as other top executives, the report said.

The report comes after Elliott sent a letter to NRG's board last

month

, pushing for a boardroom overhaul. The activist investor has had urged the company to conduct a review of its home services strategy and add new independent directors.

Elliott and NRG did not immediately respond to Reuters' requests for comment.

Elliott had

disclosed

a more than 13% economic interest in the utility company in May, which it said was worth around $1 billion, without specifying how much, if any, of that interest was in NRG stock. (Reporting by Rahat Sandhu in Bengaluru; Editing by Krishna Chandra Eluri and Maju Samuel)