Grandstand rugby league commentators David Morrow and Warren Ryan have been stood down pending an investigation into an alleged racist remark broadcast on air.

The investigation follows a reference made on air by Ryan during the broadcast of the round 11 NRL match between the Sydney Roosters and Canterbury Bulldogs on May 23.

Ryan refers to a line in a movie and says "the old darky says, 'someone says quittin' time', he says 'it's not quittin' time, I say quittin' time.' Then he yells out 'quittin' time'."

An ABC spokesperson said both commentators have been asked to submit a formal response on the matter to senior management.

Morrow was suspended last year for a racist joke for which he later apologised and said he was very embarrassed about.

Morrow has been calling rugby league for the ABC since 1980 as well as being a regular Olympic and Commonwealth Games commentator for the national broadcaster.

Ryan, a former premiership-winning coach and first grade rugby league player, has been Morrow's long-time expert co-commentator, but had previously hinted this may be his last season behind the microphone.

Friday night's NRL match between Penrith and Parramatta was called by Richard Svenson and Matt Head.

Brad Cooke and Steve Turner will call the Saturday night game between the Sydney Roosters and Canberra Raiders.