Matt Damon was "desperate" to work with James Cameron on the 'Avatar' franchise, but he has no regrets about rejecting the offer to continue with the 'Bourne' franchise.

The 52-year-old star is thought to have missed out on a $250 million payday by turning down the role of Jake Sully - which went to Sam Worthington - in Cameron's 2009 sci-fi epic, but Damon has insisted he couldn't have left his friends "in the lurch" by quitting the 'Bourne' movies.

Speaking to CNN's Chris Wallace, he said: "I’m sure it’s the most money an actor ever turned down, you know?

"I had a contract ... I was in the middle of shooting the 'Bourne' movie and I knew that we were going to need work at the end, and I had to get it all the way to the finish line and I would have to leave the movie kind of early and leave them in the lurch a little bit and I didn’t want to do that.

"I desperately wanted to work with Cameron. I mean, because he worked so rarely."

Damon - who has played lead character Jason Bourne in the five 'Bourne' movies - revealed he once told actor John Krasinski that he turned down 'Avatar', and the star insisted Damon wouldn't have changed if he had taken on the movie, apart from being rich enough have a space station.

Asked if he would've "put off the 'Bourne' series" if he had known 'Avatar' was going to be the biggest grossing movie of all time, he said: "This is like ... this is like that question.

"No it’s less much less consequential, that was just a joke. Dumb ... but no, I mean, I don’t I don’t know how I could have left the all my friends in the lurch. You know what I mean?

"It would have ... my favourite reaction to this was, I told John Krasinski, we were writing this little movie a long time ago called 'Promised Land' and we were in my kitchen and it was a Saturday morning and we were on a break.

"I said, 'Yeah,' I tell him about 'Avatar', and he launches himself out of the chair.

"He starts pacing the kitchen, he goes, 'OK, OK, OK. OK, OK. Nothing in your life would be different today if you had done that movie, except you and I would be having this conversation in space.'

"I would have been the same guy, I just would have had a space station."

In May, Damon said turning down a role in 'Avatar' was the "dumbest thing an actor ever did".

He was offered 10 per cent of the movie's box office profits if he took on the part, and by turning down the role he also missed out on the chance to team up with fellow lead actor Zoe Saldana (Neytiri).

Damon told 'Entertainment Tonight': "It’s the dumbest thing an actor ever did in the history of acting."

But Saldana told him: "I don’t think your career suffered because of it, trust me."

She joked: "I've just always felt blessed that I was picked, that I worked really hard and auditioned.

"I'm not Matt Damon. I don't get to turn down Avatars."

Damon added: "I've probably done, like, 50 movies. I've never been in a movie that made $1 billion."