SURAT THANI: Police believe an Asian man was responsible for the alleged rape of a Norwegian woman, 26, on Koh Phangan early on Sunday morning.

Inspecting the scene on the southern tourist island on Monday, police said the woman reported her case to the Koh Phangan police station at 3am on Sunday.

According to him, the woman attended a half-moon party at 11pm on Saturday. When she returned to her room at Goodtime Beach Backpackers hotel at about 2am on Sunday, she realised she had lost her wallet.

She and a male friend tried unsuccessfully to find the wallet and she decided to walk back to the place where the party was held alone.

On the way, an Asian man on a motorcycle offered her a ride to help her find the wallet but he turned into an alley opposite a Big C store and attacked and raped her there. The scene was about 100 metres from her hotel.

The woman told police that she tried to fight and her jewellery and fake nails must have dropped there, he said.

"Police are collecting evidence at the scene. Surveillance camera footage shows the suspected motorcyclist. He is Asian but his nationality remains unclear. The victim underwent a physical checkup and is under the care of tourist police," he said.

The woman arrived in Thailand through an immigration checkpoint in Krabi province on April 17. She visited Bangkok and met her elder brother there. Both arrived on Koh Phangan on May 4.