Melbourne Crime Investigation Unit detectives are appealing for witnesses following an armed robbery at a convenience store in Richmond last month.

Investigators have been told a man armed with a knife walked into the store on Church Street about 4.45am on Thursday 12 February.

The man approached the counter and produced a knife while making demands for money from the till.

The till was placed on the counter and the offender stole a quantity of cash before fleeing the scene.

He was last seen running north on Church Street.

No one was injured.

The offender was wearing a cream hooded jumper and jeans, with his face covered.

Detectives have released an image and CCTV of a man that may assist with their enquiries.