Sweltering temperatures sweeping Europe have brought a plague of jellyfish to Spain's eastern seashores, forcing holidaymakers to stay out of the sea, the Red Cross said yesterday.

The unwelcome visitors, which can reach the size of a dinner plate, have flourished thanks to a glut of plankton brought on by higher sea temperatures and a decline in natural predators like dolphins and turtles.

The Red Cross has treated more than 10,000 jellyfish stings this summer so far in the eastern region of Catalonia, a spokesman for the organisation said. "Nearly a third of those have been in the past week," he said.