Just before 11.30pm on Saturday, July 18, a marked Ford Kuga police car was parked in a locked car park when an unknown offender set it on fire.
The flames from the car then spread to another vehicle, a Peugeot 308, that was parked nearby - both cars suffered extensive damage and have subsequently been written off.
Inspector Matthew Wood said: “After reviewing CCTV footage, we have no doubt that this fire was started deliberately.
“This reckless act has resulted in two operational police cars being removed off the roads, meaning we now have less resources to respond to people when they need us.
“Thankfully no one was injured and we are now working hard to identify those responsible.
“If you were in the area on Saturday and witnessed anything suspicious, or can assist with our enquiries, please call 101 quoting incident number 1195 of July 18.”