The drought is Portugal's worst since at least 1945, when 86 percent of the territory was in severe or extreme drought. The lack of rain has led to the autumn/winter wheat harvest forecast being slashed by up 70 percent and has affected neighbouring Spain.

Thirty-nine towns with a total of 22,385 inhabitants are getting their water from tanker trucks as local reservoirs and wells dry up, the report said.

Temperatures over the summer months are expected to be higher than normal, it said.

Forests are drying up, with potential fuel showing dryness typical of August at various sites around the country. Dropping reservoir and lake levels mean water-bombing aircraft increasingly cannot land on them to fill their tanks.

The forest bureau reported that there had been 12,690 forest fires and smaller blazes through mid-June, up 55 percent over the average of the previous five-year period.