Police are investigating images of a police officer wearing gang colours being spread on social media

The images -- taken two to three years ago -- show the officer wearing a Mighty Mongrel Mob vest and hat over his uniform.

It's the second time a police officer has been seen wearing gang insignia since the patch ban came into force.

Assistant Commissioner Mike Johnson, says the photos are below professional standards, and the officer has come forward.

He says their Professional Conduct group is investigating and considering their next steps.