Photo: RLS Media

Investigators have been told the 27-year-old victim was taking footage on the Merri Creek Trail on Wednesday 21 February when he was approached by an unknown man about 11.40am.

The man produced a knife and demanded the victim hand over his camera, before fleeing along the trail towards Albion Street.

The victim was not injured during the incident.

His camera is described as a Panasonic GH5 DSLR camera with a 12-24mm lens attached.

Investigators have released a composite image of a man they believe may be able to assist with their enquiries.

The man is perceived as Caucasian, aged in his early 20s and about 170cm tall with shoulder-length blonde hair.

He was wearing a light blue V-neck jumper with rolled-up sleeves, dark shorts and white Nike runners at the time.

Police believe there would have been a number of people walking and riding their bikes along the trail at the time and urge anyone with information to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au.