An off-duty police officer has been charged with possessing cocaine at Sydney's Star Casino on Saturday night.

Police were conducting a drug dog operation at the Pyrmont casino about 9.30pm when they spoke to a 32-year-old man.

The off-duty officer was spoken to during a drug dog operation at the Star Casino. Credit:SMH

The man was a senior constable attached to the State Crime Command. He was allegedly found to be in possession of a "small amount" of cocaine, a police statement said.

A NSW Police spokesperson said the off-duty officer had since been suspended and stood down, with final decisions about the incident expected to be made on Monday.

Police standards of professional conduct say employees "must comply with the law whether on or off duty".

"In the event that you are charged with a criminal offence you are required to report the matter to your commander," the standards say. "Serious misconduct can lead to transfer, loss of income or removal from NSW Police."

The man was issued a Future Court Attendance Notice for possessing a prohibited drug and will appear at Downing Centre Local Court on Wednesday, October 23.