Doctors at Siriraj Hospital say Butsaran "Numtarn The Star 5" Thongchiew, 28, died of brain swelling at the hospital at 2.17am Friday.

Dr Prasit Wattanapa, dean of the Faculty of Medicine at the hospital, said on Friday morning that Butsaran's condition became critical Thursday evening.

Although the bleeding had stopped, her brain continued to swell, a condition that eventually killed her, he said, adding doctors had done their best to save her. The hospital would later hold a press conference to elaborate on the case.

On Thursday, Dr Prasit and other prominent doctors at the country's leading hospital told a briefing that Butsaran's haemorrhaging was an unprecedented case as they could not locate the source. The hospital management said her case was one of the world's rarest.

It was reported that her family allowed doctors to examine her body as a study on the rare illness.

On Tuesday, Butsaran suddenly bled heavily through her nose and mouth in her native province of Samut Sakhon. She was rushed to Samut Sakhon Hospital and referred to Siriraj in Bangkok on Wednesday. Through the process, she received multiple resuscitations.

Butsaran, better known by her nickname Numtarn, graduated from the College of Music, Mahidol University. She entered showbusiness by starring in a music video and a movie. She then joined The Star singing contest and appeared in a popular TV series.