The teenager had a disagreement with a group of girls and they invited her to talk it out.
But when Jenny (not her real name), 16, entered the private apartment at Balestier Road on April 1, she discovered they were not interested in talking at all.
She claimed they threw a glass at her, threatened to burn her face with a lighted cigarette and put her head under running water.
She made a police report, but one of her alleged attackers has apparently fled the country.
Jenny is a Chinese national who has been studying at a private school in Singapore since last February.
She said she had a disagreement with four female classmates, who are also Chinese nationals.
It is unclear what this was about, but Jenny's mother told The New Paper on Monday that the issue was trivial.
Jenny claimed that sometime earlier, one of her classmates had sent her an SMS to meet to settle things and invited her to a condominium in Balestier.
Jenny told Shin Min Daily News last Wednesday that when she turned up at the apartment, she was confronted by her four classmates.
She claimed they threw a glass cup at the left side of her face, cutting and bruising her.
"After throwing a glass cup at my face, they also beat me up with a clothes hanger," she said.
"They pulled my hair and pushed me to the floor. They even threatened to cut my face."
Jenny claimed she was so scared she contemplated escaping by jumping from the 19th-storey balcony.
She said when the assaults left her nearly unconscious, they carried her into the bathroom, where they poured salt on her wounds and drenched her with cold water from a running tap.
She fainted from the pain.
When she came to, she realised the apartment was vacant and that her mobile phone and wallet were missing.
She got help from someone at the condominium lobby to call the police.
A police spokesman told TNP yesterday that a report was made on the day of the alleged attack.
The police have classified the case as one of voluntarily causing hurt.