An investigation has commenced into a robbery overnight where two cleaners were injured at a restaurant in Petersham.

Shortly after 12.15am today two men entered the premises on New Canterbury Road through a rear door.

One of the men was armed with a handgun, the second a machete and they confronted the two cleaners demanding cash from a safe.

The cleaners did not have access to the safe and the offenders took personal property including wallets, a phone and a watch from them.

Access was not gained to the safe or cash register and the men fled through the rear door of the building to a waiting vehicle.

Police from Marrickville Local Area Command attended the restaurant and established a crime scene.

A 31-year-old man was taken to Royal Prince Alfred Hospital for treatment to a laceration on his neck whilst a 29-year-old man received bruising and a scratch to his cheek.

The two offenders are both described as being 170cm tall with a medium build. Both were wearing gloves and had their faces covered.