May 9 (Reuters) - Two proxy advisory firms on Thursday recommended SilverBow Resources shareholders reelect the company's nominated directors, dealing a blow to activist investment firm Kimmeridge Energy Management, which is pushing for three board seats.

Institutional Shareholder Services (ISS) and Glass Lewis each issued recommendations that back the three company directors who are standing for reelection to the company's nine-member board, according to the reports seen by Reuters.

Kimmeridge, the largest shareholder in SilverBow, is aiming to seat three new independent directors at the oil and gas producer's annual shareholder meeting on May 21, saying the company needs to revamp its governance and improve performance.

"While we acknowledge Kimmeridge's industry credibility, we do not believe there exists sufficiently compelling cause to endorse the dissident nominees at this time," Glass Lewis wrote in its report.

Both advisory firms noted SilverBow's improved operating performance in recent months was an important consideration, including how SilverBow has managed the assets it bought from Chesapeake Energy in November.

In a statement, SilverBow said the proxy advisers' support for its candidates was "further evidence that the SilverBow board is acting in the best interests of our shareholders".

Kimmeridge did not respond to request for comment.

The two reports mark the latest twist in a long-running tussle between SilverBow and Kimmeridge, which has also included public offers by the investment firm to merge SilverBow with its own private energy operator in the Eagle Ford basin of south Texas.

That offer was withdrawn by Kimmeridge in mid-April, citing a lack of credible engagement in negotiations from SilverBow.

ISS wrote that shareholders would be right to see this board fight as Kimmeridge's fourth try to acquire the company and said the SilverBow board had responded appropriately to all overtures.

"Given that these are conventional reasons for failure to consummate a transaction, and that the board seems not to have behaved in an obstructionist manner, it does not appear that additional change on the board is needed at this time," ISS said.

While Glass Lewis did not go as far, saying Kimmeridge's nominees seemed independent so would not necessarily push for a merger if elected, they struggled to see the benefits of a tie-up over management's existing strategy.

Glass Lewis also chided SilverBow for its continued use of a poison pill - a type of anti-takeover defense that stops parties from being able to accumulate significant amounts of shares - calling it "fundamentally regressive from a corporate governance standpoint". (Reporting by David French in New York and Svea Herbst-Bayliss in Boston; Editing by Chizu Nomiyama, Josie Kao and Jamie Freed)