Victoria's gambling regulator says there is no evidence to support allegations that the round 26 NRL match between the Sydney Roosters and North Queensland Cowboys was fixed.

The Victorian Commission for Gambling Regulation (VCGR) sent a "please explain" letter to the NRL after bookmakers reportedly suspended betting three times before the game when a splurge of bets backed the Cowboys to win by more than 13 points.

The Roosters, who had started favourites, surrendered a 16-0 half-time lead to lose the match 32-16.

The game, played at Sydney Football Stadium in the final round of the NRL regular season, had no impact on the make-up of the finals.

The VCGR said the NRL had fully and properly investigated the matter and recognised the importance of protecting the sport's integrity.

The NRL was approved by the VCGR as a sports controlling body for betting purposes in May last year.

"The VCGR is satisfied that the NRL continues to monitor and maintain the integrity of rugby league," the VCGR said in a statement.