(Reuters) -Bitcoin miner Riot Platforms is seeking three board seats at rival Bitfarms, a long-sought acquisition target that has rebuffed its $950 million buyout offer and adopted a poison pill to fend off any attempt at a hostile takeover.

Riot, the biggest shareholder in Bitfarms with a nearly 15% stake, withdrew the offer on Monday but said it was "ready to engage" with the company's reconstituted board about a potential transaction.

"The Special Committee is disappointed that Riot declined to engage constructively and participate in the process, and instead has continued to take steps to attempt to undermine the integrity of the process and harm the interests of other Bitfarms shareholders," Bitfarms said in a statement.

The two companies have been at loggerheads since Riot's unsolicited offer in April, which Bitfarms has said undervalued the company and begun a review of its strategic alternatives.

Riot has accused Bitfarms of lacking solid corporate governance earlier this month, setting the stage for a board battle.

Crypto miners are aggressively hunting for growth opportunities, partly to offset the hit to their earnings from Bitcoin's so-called "halving" in April.

The halving, which occurs roughly every four years to reduce the rate at which new bitcoins are created, cuts miners' rewards by half.

Riot has called for a special meeting of Bitfarms' shareholders to vote on its three director nominees - John Delaney, Amy Freedman and Ralph Goehring.

Delaney is a government and public affairs expert, while Freedman is a former investment banker who has helped boards with corporate governance matters, Riot said.

Goehring is a veteran CFO with expertise in financial, accounting and tax matters, according to the company.

All three candidates are independent of both companies and will "help oversee the strategic alternatives process at Bitfarms," Riot added.

Shares of Bitfarms fell nearly 9%, and those of Riot dropped about 4%.

(Reporting by Niket Nishant in Bengaluru; Additional reporting by Pritam Biswas; Editing by Tasim Zahid and Shinjini Ganguli)