Acting Sergeant Andrew Dunlop, of Heywood police, said the vandals set the toilet block alight at the Surrey Ridge Campground in the Cobboboonee National Park sometime between 9pm Saturday and 8am Sunday.

He said the fire was “well and truly” out by the time firefighters arrived on scene, and it was estimated that the fire started around midnight.

The damage was spotted by early morning walkers who notified police.

Acting Sergeant Dunlop said he was disappointed by the vandalism on the water tank and raised toilet block which had disabled access.

“We are looking for witnesses who may have seen people driving around late in the night,” he said.

Vehicles doing wheelies in the park had left plenty of tyre tracks, he said.