Police are investigating an attempted carjacking in Frankston last night.

A 48-year-old Frankston South man was walking to his vehicle at a Nepean Highway service station when he was approached by an unknown man at about 9.40pm.

The man, who was armed with a handgun, demanded the victim’s car keys.

The victim refused to hand over the keys and the offender struck him in the forehead with the gun, before stealing his cigarettes.

The attacker then fled to a waiting vehicle, believed to be a brown or maroon VT Commodore with no registration plates, which sped off.

The victim sustained a minor injury and did not receive treatment.

Press PLAY below to watch footage of the incident.

The attacker is perceived to be Caucasian in appearance, aged in his mid-20s, and about 183cm tall with a slim build.

At the time of the attack he was wearing a grey top, black bum bag, red underpants, black pants, white sneakers and a maroon beanie.

Anyone with information about the attempted carjacking is urged to contact Crime Stoppers on 1800 333 000 or submit a report at crimestoppersvic.com.au.