Police were called by the Country Fire Authority overnight to a suspicious fire in an external compacter at Stockland Wendouree which took almost an hour to extinguish.
The fire in a loading bay was reported at 11.15pm on Friday and was attended by five trucks and around 20 firefighters.
Police believe the unknown offender deliberately set fire to recyclable material in the compacter at around 11pm.
A Victoria Police spokesperson confirmed the incident was being investigated.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report to www.crimestoppersvic.com.au.
Sign up for our newsletter to stay up to date.