A senior Koch Industries executive is disputing a new book that says Fred Koch, the father of billionaire brothers Charles and David Koch,helped build a Nazi oil refinery.

In the letter to company employees, David Robertson, president and COO of Koch Industries, said Fred Koch’s work for the Nazi regime was one of many international projects and predated World War II,according to the New York Times.

“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 story line is grossly inaccurate,” Robertson said.

In Dark Money, a new book about the political influence of some of the country’s wealthiest families, New Yorker staffer Jane Mayer writes that one of Koch’s projects was a major oil refinery for Nazi Germany, which Adolph Hitler personally approved, according to the book.

Koch Industries and the Koch brothers, known for funding conservative political candidates, have previously criticized Mayer’s reporting on their family.

This article was originally published on Time.com.