"To call this book pure nonfiction would be inaccurate," Frey writes. "It is a combination of fact and fiction, real and imagined events."
Frey has acknowledged that major sections of "A Million Little Pieces," his million-selling memoir of addiction and recovery that Oprah Winfrey endorsed, then ridiculed, were fabricated. Some of the revelations, first reported by the investigative Web site The Smoking Gun, also raised doubts about "My Friend Leonard."
Frey now acknowledges that "significant" parts of "My Friend Leonard," a best-selling story about his friendship with a gangster, were also invented.
In "A Million Little Pieces," Frey writes of a three-month jail term that he later acknowledged never serving.
As The Early Show national correspondent Tracy Smith reported, new copies of "A Million Little Pieces" include three additional pages: an apology from Frey.
The apology says in part, "My mistake, and it is one I deeply regret, is writing about the person I created in my mind to help me cope, and not the person who went through the experience."
"My Friend Leonard" also begins with the author behind bars, getting hit in the head by a "three-hundred-pound man named Porterhouse."
"I did not spend ninety days in jail, and Porterhouse is a fictional character," he writes. "Many of the other characters' names and identifying characteristics have been altered or fictionalized, as have major events in their lives."
"My Friend Leonard" was published last year by Riverhead Books, an imprint of Penguin Group USA that reportedly has dropped the author.