By James O'Brien
The Foreign Office has amended its travel advice for Greece, with Britons being warned jellyfish blooms have been spotted in the Mediterranean.
There have been previous warnings this summer about jellyfish just off the coasts of France and Italy.
However, local marine biologists insist this year is the same as years gone by and that the blooms are made up of non-stinging species.
They assured holidaymakers they are keeping a close eye on the situation.
A Foreign Office spokeswoman told BBC News: "We have been alerted to large numbers of jellyfish in the Mediterranean this summer, especially in a number of key holiday destinations for UK tourists.
"We have updated our travel advice for a number of Mediterranean countries to reflect this issue."
The spokeswoman said the Foreign Office would keep its advice "as informative and useful for visitors as possible".
Professor Stefano Piraino is a marine biologist at the University of Salento in southern Italy and project co-ordinator of the Mediterranean JellyRisk programme.
Piraino admitted the Mediterranean was no different to a lot of other places around the world in that it had seen a rise in jellyfish.
But he moved to allay any fears holidaymakers may have by saying the jellyfish are typically not harmful.
"Of course, as in any other ocean or sea in the world, there might be some problems," he said.
"In the Mediterranean, we are lucky and do not have deadly [jellyfish].
Piraino said the JellyRisk programme, which is also made up of researchers from Spain, Tunisia and Malta, was launched amid fears of a rising number of jellyfish on human activities in the region.
He said the programme was concentrating on a citizen science campaign.
"This is a very important tool.
"We have, since 2009, used this approach where we are asking tourists, sailors, fishermen, divers - all the people that are in the sea - to send information about the presence of jellyfish," he told BBC News.
The research team has created a smartphone application that gives people the chance to send and receive information about how many jellyfish are in their area.
The app includes details on treating different types of stings.
"We have collated scientific evidence and results from clinical trials which we have reviewed, so we can now, through the app and printed material, offer advice on the treatment of stings," Piraino added.
Anti-jellyfish nets will also be set up at various beaches to see how affective they are.