A mystery man is alleging that Bruce Jenner had an ongoing affair in the late 1980s.

RadarOnline reports TV producer and journalist Richard Laskos recently revealed such revelations, adding that he claims the man who has the affair with Jenner is a close friend of his and has shown him photos of the two together over the years.

"When I was over at his house, he showed me two or three photos of himself with Bruce," said Lasko. "They were both shirtless and wearing swim trunks, posing for the camera standing up. The pictures appeared to be taken on a beach. There were palm trees in the background."

Jenner, 65, emphatically told Diane Sawyer that he is not gay during a recent TV interview, where he shared news of his sex transition.

"I am, as far as I know, heterosexual," he said.

RadarOnline claims it is withholding the name of the mystery man, but based on the photos in question it describes him as a "tall, beefy 20-something at the time" the images were taken.

"I got the distinct impression from the way he'd kept the photos that they had a real relationship," said Lasko, estimating that Jenner appeared to be at least 10 years older than the man. "That it wasn't a one-night stand."

Most recently, Jenner spent several years married to Kris Jenner, and the two have a pair of teenage daughters, Kendall and Kylie. To this day, Jenner has continued to say that he has never been with a man and often points to his other two marriages as to Chrystie Crownover and Linda Thompson as added proof of his attraction to the opposite sex.

In addition to the Sawyer interview, Jenner is also slated to star in a Bravo Network docuseries about his changing lifestyle later this summer.