SINGAPORE - A 32-year-old woman has been missing for almost a week, with her friend turning to social media to ask for help in locating her.

Ms Charmaine Teo Xiu Hui, who previously worked at a call centre, went missing last Tuesday (Nov 21), her friend and former polytechnic schoolmate Ms Law told The Straits Times.

Ms Teo has been living with Ms Law and her parents in Woodlands Circle for 12 years after she became estranged from her family.

Ms Law, 35, told ST on Monday that she discovered Ms Teo was not at home when she tried calling her last Tuesday night and realised her phone was not switched on.

"She left nearly everything in the house," she said. "Her NRIC, her passport, her debit card, phone and keys."

Ms Teo had told her she was going to bed, but instead went out with a small bag.

In a Facebook post on Nov 22, Ms Law called for netizens to call the police if they saw Ms Teo, who is about 1.5m tall.

Ms Teo has a wound on her head that requires dressing to prevent infection, said Ms Law. She sustained the wound as she hit herself with a brush repeatedly at night, and then applied ice to it, causing a cold burn.

She was hospitalised in Khoo Teck Puat Hospital for 33 days from mid-September to mid-October for the wound.

This is not the first time she has gone missing, Ms Law said. In July this year, she went missing and the police found her six days later.

"She slept on the streets," said Ms Law. "She was sent to the Ministry of Social and Family Development, and they sent her to the Institute of Mental Health, but the doctors declared her free of mental illness."

Ms Teo has a younger sister and brother. Her sister, Ms Samantha Teo, a 30-year-old clinical trial administrator, told ST that the family is aware that Ms Teo has gone missing.

"I went out looking around when Ms Law told me that she was spotted in Yishun," she said.

Ms Teo moved out 12 years ago due to issues with her mother, and Ms Law and her parents treat her like their own family.

Although she has been spotted by several netizens at Yishun and Ang Mo Kio, she has still not been found.

Ms Law urged those who spot Ms Teo to call the police immediately.

The police sent out a missing person notice on Friday (Nov 24).

The notice said Ms Teo was last seen at Block 729, Woodlands Circle, on Nov 21 at about 9.50pm.

She was wearing a red shirt, black pants and a black cap.

Anyone with information on her whereabouts should call the police hotline at 1800-255-0000 or submit information online at www.police.gov.sg/iwitness.

All information will be kept strictly confidential.