Greater Dandenong Crime Investigation Unit detectives are investigating after two men held up a milk bar earlier this month and fled with cash.

Investigators have been told the men, who were armed with firearms, entered the Heatherton Road store about 9.30pm on 20 July and demanded money.

The owner, a 47-year-old Dandenong man, was assaulted during the incident and taken to hospital with minor injuries.

The pair took a small quantity of cash, several packs of cigarettes and a mobile phone before fleeing on foot along a nearby laneway.

The second victim, a 42-year-old Dandenong woman, contacted police.

She was not injured.

One of the men is perceived as being of African appearance, about 170cm tall and aged between 20 and 30 years old with a slim build and Australian accent.

The second is perceived as Caucasian in appearance, about 175cm tall and aged between 20 and 30 years old with a slim build.

He was wearing a light-coloured hoodie and was carrying a black bag.

No arrests have been made at this stage and the investigation is ongoing.