In a statement the government warned that there was "a health risk in case of contact" with the jellyfish, advising anybody stung to wash the affected area with seawater and not rub it as that would cause the poison to spread.

"Yesterday (Monday) there were many in the water but today it's a little calmer," a Red Cross spokesman told AFP by telephone from the southern town of Salobrena.

In the eastern tourist mecca of Benidorm, which reported a jellyfish alert on Monday, the municipal councilllor with responsibility for beaches Josefa Perez said a shoal of the creatures had moved further out to sea and the threat to bathers had receded.

A new symbol -- a white flag with blue jellyfish depicted -- has been created this year to warn swimmers of any danger. It can be seen fluttering alongside the usual green, yellow and red flags indicating swimming conditions.

Environment Minister Cristina Narbona and ecologists have put the jellyfish invasion down to rising water temperatures.

Professor for the Mediterranean Institute of Advanced Studies, Carlos Duarte, told El Pais newspaper that overfishing also played a part as there were now fewer natural predators in the sea to feed on the jellyfish, thereby reducing their numbers.