CJOB News Team reporting
Local media reports and a relative have identified the pair as 20-year-old Audrey Belanger and 26-year-old Noemi Belanger.
The cousin, who did not want to be identified, says the sisters' parents have been notified of the deaths.
A local newspaper quotes a spokesman with the Phi Phi Island police saying became aware of the deaths Friday night after the two tourists' bodies were found in a hotel room.
Poisoning is suspected but tests are being done to try to determine the cause of death.
The bodies were believed to have been in the room for 12-20 hours before they were discovered by concerned hotel staff.