POLICE are investigating the cause of a fire in a demountable toilet block at the Moscow Circus.
The fire was first reported 1.20am Wednesday, with two crews of firefighters extinguishing the blaze by about 1.35am.
There were no injuries and the fire was confined to the small toilet block, which was brought to Len Johnson Oval at North Ipswich for the Moscow Circus.
Police believe the fire is suspicious and officers kept the area under guard today while scientific examinations took place.
Anyone with information should contact Crime Stoppers on 1800 333 000.