Charles Koch. A new book claims that his father helped the Nazis build an oil refinery. Photo: Screenshot.

The president of Koch Industries rebutted claims in a new book about billionaire families that the late Fred Koch had financial dealings with the Nazis, The Blaze reported on Tuesday.

Dave Robertson called the allegations — made by New Yorker staff writer Jane Mayer in her soon-to-be-released Dark Money: The Hidden History of the Billionaires Behind the Rise of the Radical Right — “reprehensible” in a letter he sent to Koch employees on Tuesday.

Robertson called it “a sad commentary on today’s political and media environment” that the Koch family needs to refute such a “false and horrific charge.”

Mayer’s book focuses on billionaire families linked to libertarian and conservative movements, according to The Blaze. It is set to be published on Jan. 19.

According to Mayer, Fred Koch helped the Nazis in the 1930s build the third-largest oil refinery in Germany — a project ostensibly approved by Hitler — which provided German planes with the fuel needed to carry out genocidal attacks across Europe, The Salon reported. Mayer claims Koch and American Nazi sympathizer William Rhodes Davis were partners in this endeavor. The book also states that Koch “hired a fervent Nazi as a governess for his eldest boys.”

Robertson said, “To state that Fred Koch was ‘hired to build the third-largest refinery in the Third Reich, a critical industrial cog in Hitler’s war machine’ is an outrageous assertion,” Robertson said. “To cherry-pick one project among hundreds during this time frame and then use it out of context in order to further an agenda-driven storyline is grossly inaccurate.”

He explained that Koch Industries conducted an “extensive archival search” to refute Mayer’s claims, and research revealed that Fred Koch’s contract with Foreign Oil was signed on Sept. 8, 1933, nearly six years before Germany invaded Poland. The oil refinery became operational on March 23, 1935, according to Robertson.

“Suffice it to say, Fred Koch opposed all forms of tyranny,” Robertson concluded in his letter. “He was a great man who built a great company. Under the leadership of his son Charles, we are proud to continue his legacy.”

Robertson noted that officials at Koch Industries declined to participate in Mayer’s book and have not read it.