Police have released CCTV footage following an armed robbery at a supermarket in Docklands this morning.

Investigators have been told a man allegedly threatened staff at the Lorimer Street supermarket with a sawn-off shotgun and made demands for cash about 8.15am.

The man stole cash and other groceries and left on foot.

He travelled east on Lorimer Street and was last seen heading north on Wurundjeri Way.

The offender is perceived to be of Caucasian appearance, about 172cm tall, aged between 25-35 with a thin build.

He was wearing a black hoodie with a green motif on front, dark pants and black and white shoes.

The man was carrying a large red backpack with black straps.