Two Canadian sisters found dead in a Thai hotel room may have been killed by poisonous blowfish or mushrooms, it has been suggested.

Noemi, 26, and Audrey Belanger, 20, were discovered by a maid at their hotel on the resort island of Phi Phi, three days after they were last seen on a night out.

The siblings were covered in vomit, had skin lesions and were bleeding from their gums when their bodies were discovered, according to Thai officials.

Investigators found no evidence of a struggle in the hotel room and ruled out foul play.

Police Lieutenant Colonel Jongrack Pimthong told the Associated Press: "There were neither signs of fighting, nor of robbery, but we found many kinds of over-the-counter drugs, including ibuprofen, which can cause serious effects on the stomach."

The Phuket News reported that Dr Komkrit Phukrityakame, director of Krabi Hospital, carried out the initial examination on the bodies.

Phukrityakame said he suspected the pair had been poisoned by a meal that included blowfish or poisonous mushrooms.

The sisters were from Pohénégamook, 170 kilometres northeast of Quebec City on the border with Maine.

The close-knit community has been rocked by the new of their deaths.

Joanie Ouellet, a former colleague of one of the sisters, told the Daily Mail: "The mood is quite sad in the town today."

Blowfish is a delicacy in Japan, but it can be extremely deadly if it is not prepared properly.

Its poison, called tetrodotoxin, is nearly 100 times more poisonous than potassium cyanide and can cause death within 90 minutes of consumption.

IBTimes UK takes a look at other exotic delicacy's that could potentially kill those brave enough to try them.