The warning comes as the body of an American tourist has reportedly been found on the Greek island of Mathraki, adding to the list of foreigners missing or reported to have died during the record-setting heatwave.
A Dutchman also was found dead on Samos over the weekend, following the recent death of British TV presenter Dr Michael Mosley on the island of Symi. Adding to the list, two hikers were found dead on 5 June on Crete. Another American, Albert Calibet, is among at least three others reported missing.
