The Nobel prize-winning author is listed in "Spies: The Rise and Fall of the KGB in America," Yale University Press, co-written by John Earl Haynes, Harvey Klehr and Alexander Vassiliev from notes Vassiliev took in Moscow archives.
A former KGB officer, Vassiliev was provided with access in the 1990s to Stalin-era files, The Guardian reported.
In the book, Hemingway is referred to as a "dilettante spy." His file says he was recruited in 1941 before he went to China, the book claims. He was called "Argo" and allegedly met with Soviet agents in Havana and London in the 40s, The Guardian reported.
The books described Hemingway as enthusiastic, but not very effective, and said Soviet contacts with Hemingway ended by the end of the decade.
"Spies" doesn't say whether the authors believe Hemingway was serious about spying or looking for material for a book.