Drones and helicopters fitted with thermal imaging cameras will stalk Melbourne’s rail network to stop vandals disrupting commutes during the busy grand final weekend.

The devices will allow authorities to respond to trespassers in real time, with data sent to the Metro Trains control centre and Victoria Police.

“We want to make sure we can keep the network moving,” Transport Minister Jacinta Allan told reporters on Monday.

“This technology also helps us to respond as quickly as possible to incidences where they arise.”

It’ll be ramped up during busy events to minimise disruption to rail services when demand is at its highest.

Ms Allan said “graffiti vandals cause a lot of frustration for passengers”, and this would send a clear message that they are being watched and will be pursued.

Detective Inspector Andrew Gustke said police intelligence would decide where and when the drones and helicopters are deployed.

“We want to try and stop this behaviour, this criminal activity, before it starts because the downstream effect of this sort of disruption to the rail network is very disruptive,” he said.

“The key message that we really want to get out to the community is that these offenders, these criminals, are being watched.”

Three drones could be used on the network at any particular time.

Helicopters and drones fitted with cameras and thermal imaging devices have already been used to watch the rail network during events like White Night, New Year’s Eve and the Spring Racing Carnival.

There are more than 9000 CCTV cameras at train stations and Metro Trains spends $10 million a year fighting graffiti.

The free tram zone will be extended from Wednesday to reach the MCG before the grand final on Saturday.

Extra train services will also be added to the network to cope.