Matt Damon reveals why he turned down James Cameron's offer of the lead role in Avatar

Matt Damon passed up a hefty paycheck when he turned down the lead role in Avatar. Photo / Getty Images

Matt Damon has revealed why he turned down the lead role in Avatar - a decision which meant he missed out on earning at least $250 million USD ($398m NZD).

The 48-year-old actor told GQ magazine Avatar's director James Cameron offered him the role and 10 percent of the film's worldwide profits.

"When [Cameron] offered it to me, he goes, 'Now, listen. I don't need anybody. I don't need a name for this, a named actor. If you don't take this, I'm going to find an unknown actor and give it to him, because the movie doesn't really need you."

Damon said his role in the Bourne films prevented him from accepting the role.

"It would have caused a problem for [director of The Bourne Ultimatum] Paul Greengrass and for all my friends on The Bourne Ultimatum, so I couldn't do it."

Christian Bale, left, and Matt Damon attend a premiere for Ford v Ferrari on day five of the Toronto International Film Festival. Photo / AP

Avatar went on to gross $2.789 billion USD worldwide following its 2009 release, and the lead role of Jake Sully was played by the then-unknown Australian actor Sam Worthington.

Damon said he doesn't regret missing out on the paycheck, but he does regret passing up the chance to work with James Cameron.

"I realised in having to say no that I was probably passing on the chance to ever work with him. So that sucked and that's still brutal."

The Oscar-award-winner is currently promoting his new movie, Ford v. Ferrari which also stars Christian Bale.