It is believed that a woman entered the toilet block and was confronted by a man shortly before 12pm.
The woman was threatened with sexual assault but she managed to flee to safety, after which the offender fled the scene.
The attacker is described as being of Mediterranean/Middle Eastern in appearance, aged in his 40s, with mousy brown hair and a thick accent.
He was last seen wearing a black hooded top and black pants with a white stripe down the side.
Anyone with information is asked to contact Crime Stoppers on 1800 333 000.
