The woman said she was assaulted by a motorbike taxi driver who picked her up from Kuta. Picture: iStock

The Perth woman, who cannot be identified for legal reasons, left Paddy’s Bar in Kuta in the early hours of Tuesday and began walking along Legian Road near Bali’s popular tourist beach.

It is alleged a motorbike taxi driver — commonly referred to as an ‘ojek’ — offered her a free lift to her hotel before attacking her.

Security guards at Jayakarta Hotel, which is near the spot where the alleged assault took place, heard screaming.

One of their officers ran to help but by the time they arrived the man had fled, the hotel’s security told AAP.

Several hours later the woman, along with her friends, went to Kuta police station to complain.

Denpasar Police Detective Chief Reinhard Habonaran Nainggolan said they are investigating the matter but are facing “difficulty” because the woman did not want to undergo forensic testing.

“She was stressed and crying (when she made the report),” he told reporters on Wednesday.

“She said she doesn’t want (to take the forensic examination) because she wants to go back to Australia.

“I told her this is very difficult to process her police report (without examination).”

It is not known whether the woman has already returned to Australia.