Police are investigating a suspicious fire at a skate park in Mount Gambier.

Just before 7pm on Thursday police and MFS crews were called to O’Connor Drive after reports a park shelter was set alight.

Firefighters extinguished the blaze but the shelter was substantially damaged.

A man on a BMX bike was seen in the area around the time of the fire.

He is described as wearing a green hoodie with a cream and white backpack and a

green BMX bike.

A police spokesperson said it was important to remain vigilant and report suspicious behaviour to the Police Assistance Line on 131 444.

Contact Crime Stoppers online at www.crimestopperssa.com.au or via phone on 1800 333 000 to report any information.