Thieves have allegedly used a forklift to steal a ride-on lawn mower, tools and a classic vehicle worth $300,000 from a property in Melbourne's outer north-west.

According to media reports, the offenders gained access to the commercial property on Hamilton Road in New Gisbrone by cutting a locked gate.

Police say the offenders stole a truck and trailer and used a forklift inside to load the truck with a ride-on lawn mower, water tanks, tools, water pumps and electric tools.

The offenders fled the scene, driving two pickup trucks, one with the trailer attached, followed by the stolen Ford Falcon and truck.