The body of a woman was found in Whampoa River near Blk 110 McNair Road on Thursday morning just after sunrise.
The police said they received a call about the body at 7.33am. Paramedics from the Singapore Civil Defence Force (SCDF) also responded to the case a few minutes later at the canal between McNair and St George's roads.
SCDF rescuers then manually retrieved the body from about 2 metres from the river bank and pronounced the woman dead at 8.28am.
The Straits Times understands that the woman, who was believed to be topless and only wearing a pair of black pants, was decapitated. SCDF divers were spotted conducting a search in the canal at low tide later in the morning.
The police have classified the case as an unnatural death and are investigating.