Olivia Newton-John says it's only human to wonder what happened to her ex-partner Patrick McDermott, who has reportedly been seen alive after disappearing in 2005.

The Grease star and McDermott had been dating for nine years when he disappeared off a fishing boat in California.

Newton-John told the Nine Network's 60 Minutes program the aftermath of his disappearance was a tough time.

"Yeah it was very hard. He was lost at sea and nobody really knows what happened," Newton-John told Nine.

Reports from 2009 and 2016 claim McDermott is still alive and living in Mexico.

When asked if she wondered whether McDermott was still alive, Newton-John said: "Of course."

.@Olivianj has never really talked about the controversy over her former boyfriend Patrick McDermott, who went missing in 2005. #60Mins pic.twitter.com/Ss6eLHTpOr

— 60 Minutes Australia (@60Mins) September 25, 2016

"I mean it's human to wonder. But you know ... those are the things in life you have to accept and let go," she said.

"Because whenever you go through difficult times there's always those concerns. But you know, I live on, and of course questions come up, that's human."

AAP; Top Photo: Getty/60 Minutes

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