Police are investigating suspicious betting on one of the major awards in last year's Dally M Medal ceremony.

The Sydney Morning Herald can reveal the NRL had asked police to probe wagering trends on the Dally M Coach of the Year, won by Melbourne's Craig Bellamy.

The award is one of the major honours on the NRL's night of nights, with Bellamy pipping a strong field that included the Roosters' Trent Robinson, Canberra's Ricky Stuart, Parramatta's Brad Arthur and the Sea Eagles' Des Hasler.

Bellamy wasn't considered the favourite to win the award despite the Storm enjoying another incredible regular season en route to the minor premiership.