TORONTO - Toronto police have issued a warning about what they say is a potentially dangerous -- and prohibited -- cosmetic procedure.

Police say illegal buttock-enhancement procedures are being performed in people's homes and hotel rooms.

They say women are paying cash, typically thousands of dollars, to have a substance advertised as a synthetic filler (polymethylmethacrylate) injected into their buttocks.

Investigators say some of the women have experienced serious medical complications and ended up in hospital.

They say this type of procedure can cause long-lasting problems and even death when done outside of a medical facility.