According to her complaint with police, two unidentified persons entered her room at around 2.30am. While one of them restrained her, the other man raped her.
The woman suffered injuries during the assault and was in a traumatised state after the incident. She made a complaint to the police the next evening.
Police have registered a case of rape on the basis of the victim's statement. She has left for Bangalore.
Forensic evidence collected from the room had been sent for analysis and phone call details of the guests at the resort at the time of the crime and the staff members were being verified, an Inspector, part of the investigating team, said.
The resort is under surveillance and the staff members had been questioned.
CPI(M) leader VS Achuthanandan asked the state government to institute a criminal inquiry into the incident.
In a statement in Thiruvananthapuram on Sunday, he demanded that the owner of the resort also be brought under the ambit of the probe for rendering the premises insecure for women despite the star-category status it holds.