SYDNEY, Jan. 10 (Xinhua) -- One of the world's most venomous jellyfish has been spotted off Australia's Queensland state, sparking warnings by aquatic rescue authorities for swimmers to stay out of the affected waters.

A specimen of the Irukandji, which live in Australian marine areas and is also one of the world's smallest jellyfish at about the size of a thumb, was found by surf lifesavers over the weekend near the popular Fraser Island tourist spot and sent to specialists for identification, the Surf Life Saving Queensland rescue authority said in a statement on Tuesday.

The discovery means beachgoers must be "extra vigilant about their personal safety", the authority's regional manager Craig Holden was quoted as saying, amid the peak summer tourist season.

"We're urging everyone to stay out of the water entirely on that western side of the island while conditions are hot and humid," he said.

The Irukandji's sting can cause severe pain in the muscles, chest and other parts of the body, as well as vomiting and breathing difficulties, according to state ambulances services. Victims are advised to douse the sting area with vinegar for at least 30 seconds and call for medical assistance.

A spate of serious jellyfish stings on the island reported in 2016 and 2017 prompted more checks for the marine threats and upgrades in safety advice for the region, the aquatic authority said.