The womens' bodies were found in gruesome conditions, reportedly with large quantities of vomit and skin lesions, authorities said.
Noemi Belanger, 25, and Audrey Belanger, 20, of Quebec, were found dead in their room at the Phi Phi Palm Residence Hotel on the Phi Phi Island in the Krabi province on Friday.
Thai newspapers have reported that eating blowfish or poisonous mushrooms could have caused the deaths, but police say the cause of death is still unknown.
