Myers was reported to be working on a follow-up to 2002's Austin Powers in Goldmember and a stage adaptation in 2011, but little more information has been released in the last six months.
Filmmaker Roach has now spoken about the long-rumoured film, saying that he would return for a further sequel "in a second".
"You know, that's always up to Mike. It's always going to be, 'Does he feel like he's got what he wants?' And what the audience wants, frankly," Roach told The Huffington Post.
Roach added of Myers's high standards: "He's very audience-conscious to make it a welcomed fourth."
It has been speculated that a fourth Austin Powers movie would shift focus to Dr Evil, but Myers has not publicly confirmed those rumours.
Austin Powers in Goldmember took in $296m at the global box office a decade ago.
Watch a trailer for Austin Powers in Goldmember below: