The NRL has rejected Manly's submission to seek a career-ending injury exemption for Brett Stewart that would have seen the now-retired fullback excluded from the club's salary cap this season.

Fairfax Media understands the NRL didn't believe Stewart suffered a one-off career ending injury, rather it was the toll of years of major knee problems that led to the 31-year-old pulling the pin on his career ahead of the 2017 season.

The NRL is still examining the submission put forward for Steve Matai, who - like Stewart - has been dogged by injuries throughout his career on the northern beaches.

It is the same submission put forward last year by their former premiership-winning teammate Anthony Watmough, who collided with Beau Scott during a Parramatta Eels pre-season training session leading into the 2016 campaign.