Queensland police are investigating an assault which may have involved an off-duty police officer at a Gold Coast casino.

An off-duty police officer may have been involved in an assault on a man at casino, Queensland police say.

The Ethical Standards Command says reports suggest that two men, one an off-duty police constable, were involved in an assault on a 38-year-old man at a Broadbeach casino about 2.40am (AEST) on Sunday.

The victim had minor injuries and was taken to the Gold Coast University Hospital for observation.

Ethical Standards says no complaint has been made by the victim, but they are investigating the incident.