Michael J. Fox has recalled his "surreal" encounter with Princess Diana in 1985.

The actor has reflected on one of the most memorable moments of his decades-long acting career, which began in the early '80s.

"It all got so crazy," Michael told People of the early years of his career. "There's nothing I could think of that wouldn't happen."

The Family Ties star went on to reveal that he was seated next to the late royal at the London premiere of his film Back to the Future in December 1985.

"With the royal premiere of Back to the Future, I sat next to Princess Diana," he said. "I realised if I was like a fake yawn and an arm stretch away from being on a date with her. That one, and just moments like that, were so surreal."

Diana, who died in a car crash in 1997, attended the premiere wearing a burgundy velvet dress with a plunging back and a pearl necklace.

The 62-year-old previously spoke about sitting next to the royal during an appearance on The Tonight Show Starring Jimmy Fallon.

"The movie started and also I had to go pee," he recalled at the time. "So for the rest of the movie, I'm sitting there, like, dying."

Michael continued, "I can't say anything to her and I can't walk away from her because I can't turn my back on her. So it was just agony it could have been the greatest night of my life but it was just a nightmare. A pee-holding nightmare."