Norwegian shipping billionaire John Fredriksen has clashed with another tanker company after his tumultuous attempt to buy Euronav NV was abandoned earlier this year.

Seatankers Group, through which Fredriksen manages his shipping investments, said in an open letter to International Seaways Inc. that it would withhold its vote for the reelection of two board members at the annual stockholders meeting, including Chief Executive Officer Lois Zabrocky. Seatankers first invested in the company through an affiliate entity last year.

Seatankers “encountered a disheartening level of entrenchment, self-interest, and a steadfast refusal to even consider” proposed value-enhancing initiatives, the letter said. Some the board and management members have “shamelessly” taken credit for the outperformance of shares in International Seaways, which Seatankers said was driven in part by its own reputation of creating value.

In its rebuttal, New York-based International Seaways said the statements made in the open letter were misleading, and that it was notable Seatankers is targeting two of the three women on its board without explanation.

It’s not the first time that Fredriksen has entered into a boardroom battle with a listed oil tanker company. He attempted to merge Frontline Plc and Euronav into the world’s largest listed tanker business, before eventually scrapping the deal earlier this year. The tumult ultimately led to the resignation of Euronav CEO Hugo de Stoop.

Seatankers also said it would vote against a poison pill plan, designed to deter the group from acquiring a controlling stake in International Seaways, insisting it had no plans to take over the company.