Police are hunting for a mysterious man after a teen sunbather reported being sexually assaulted by him on a popular beach on New Year's Eve.
The woman had been lying on a beach towel on Thomson Bay Beach, on Rottnest Island off the coast of Perth, Western Australia, on December 31.
Police say the teenage girl was assaulted by an unknown male between 10:15am and 12:30pm on the busy beach.
The woman had been lying on a beach towel on the sand on Thomson Bay Beach, at Rottnest Island (pictured) off the coast of Perth, Western Australia, on New Year's Eve
The teenager had been wearing a black bikini with a white sundress over the top at the time of the alleged attack and had been sitting north of the ferry jetty.
Police say 'numerous' people were in the area at the time, as crowds gathered to ring in the new year on the picturesque beach.
They would like to speak to anyone who remembers seeing the woman or a man acting suspiciously in the area on December 31.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000.
Police say 'numerous' people were in the area at the time, as crowds gathered to ring in the new year on the picturesque beach off the coast of Perth, Western Australia