Police are appealing for witnesses following an armed robbery at a retail store in South Yarra last month.

Detectives have been told a man entered the store on Chapel Street just before 6pm on Wednesday 13 June.

It is believed the man produced a handgun before demanding the shop assistant open the till to the cash register.

The bandit grabbed cash from the till and fled the scene.

Investigators said the offender then ran to another retail store across the street where he also produced the handgun at the female assistant, demanding she open the till.

The woman refused to open the till and the man ran from the store empty handed.

He was last seen walking towards Cliff Street in Prahran.

The man is described as being 180cm tall with dark blonde hair pulled back into a pony tail.

He was wearing a long navy overcoat.