Koch Industries kicked back at a forthcoming book that suggests the company’s founder did business with the Third Reich and admired the Nazis before the start of World War II.

“It is a sad commentary on today’s political and media environment that we even have to address such a false and horrific charge,” a top company executive wrote in a letter that went to more than 100,000 Koch employees around the globe. “The implication that Fred Koch sympathized with one of the most tyrannical regimes in history is reprehensible and represents the lowest form of journalism,” wrote Dave Robertson, the president and chief operating officer of Koch Industries. The letter was posted on a company website late Tuesday afternoon.

To refute the claims in the forthcoming book, “Dark Money,” by New Yorker writer Jane Mayer, the firm examined archival corporate records, Robertson wrote. At the time, he said, the Winkler-Koch company, as it was then known, “worked on hundreds of other international projects” in nine countries, including the United States. In 1933, six years before Germany invaded Poland, Winkler Koch agreed to build a part of a planned refinery near Hamburg, Germany. At that time, Robertson said, “many iconic U.S. companies were doing business in Germany, including Coca-Cola, General Motors, Ford and IBM.”

The memo accused Mayer of cherry-picking one project among hundreds, in which Koch provided only part of the work. Using this fact “out of context in order to further an agenda-driven storyline is grossly inaccurate,” it said.

Mayer has written about the Kochs previously for the New Yorker and encountered disagreement and criticism from family members then. Her forthcoming book examines the political influence of several leading conservative families over the past five decades and the extraordinary sums they invested in libertarian and conservative nonprofit think tanks and activist organizations. Despite the broader view, Mayer’s book concentrates on the Kochs, including descriptions of deep divisions and disputes that occurred among Fred Koch’s children. Robertson’s memo does not address other findings in Mayer’s book, except to say that “many of the other claims made about the Koch family are even more preposterous” than the allegation that Fred Koch was sympathetic to the Nazis.

Mayer responded Tuesday evening in an email statement underlining her finding that the family patriarch contributed to the Third Reich. She cited academic literature on the topic but also the Tuesday statement from Koch Industries. “As the Kochs are confirming, Fred Koch was integrally involved in the creation of a German refinery that Adolf Hitler personally green-lighted,” she wrote in an email to The Washington Post. Her book points out that Fred Koch sought to enlist in the U.S. military after the start of World War II.

The Washington Post’s Alice Crites contributed to this report.