SIGNS placed on the holiday island of Koh Lanta warning visitors about jellyfish stings were blacked over by locals, a seminar on marine stingers was told on Phuket today.

Dr Somchai Bussarawit, who has been leading Thailand's research on jellyfish, told the gathering that it was important to be honest about risks in the water.

''People must be told the facts accurately,'' he said. ''This is about telling people how to be protected from danger. They have to be warned.''

His comments follow the death of a Swedish woman tourist from box jellyfish stings on Langkawi late last month, a significant event that the mainstream Malaysian media has so far failed to report.

By contrast, reaction to the global spread of jellyfish and its likely effect on Phuket has been to involve the tourism industry in an open fashion.

Phuket's mangrove east coast is a nursery for some non-deadly species, Dr Somchai told about 30 representatives from local authorities, resorts, hospitals, tour busnesses and the Public Health office today.

Dr Somchai and two Public Health officials have recently completed study tours to Australia, where the spread of box jellyfish and the much smaller irakanji is being closely monitored.

While there is no cause for alarm, the Langkawi fatality and the death of an 11-year-old Swedish tourist on Koh Lanta in April 2008 are indications that highly toxic Chironex box jellyfish are already in the region.

Other deaths attributed to the ''boxie'' have previously been recorded in the Gulf of Thailand.

Worldwide, jellyfish are spreading and adapting rapidly as their natural predators are overfished or neglected.

Phuket's popular west coast beaches were invaded by non-deadly jellyfish in January last year.

Researchers believe an ususual stream of colder water drew them up from the deep to Patong, Nai Harn and other Phuket beaches.

Thailand has become the regional centre for advanced jellyfish research, with the Department of Epidemiology in Bangkok organising today's seminar.

Vinegar, the only known treatment for the worst of the jellyfish stings, has been widely distributed to resorts and other key points around the coast of Phuket, Phang Nga and Krabi.

Experts at the seminar included Dr Potjaman Sirirayaporn, Dr Rojana Watanarangsan, and Dr Lakana Thaiker. Among the audience were Sea Canoe environmentalist John Gray and Nick Anthony of Indigo Real Estate.