Firefighters from France arrived in Greece on Thursday evening to assist in the battle against raging wildfires as thousands more fled their homes near the capital.
The 82 French firefighters were expected to intervene on Friday, a French official said.
Two more firefighting planes from France were also expected to be dispatched, as well as reinforcements from Sweden, Austria and Bulgaria.
Israel will send 15 firefighters and a large shipment of fire retardants in a civilian plane as soon as possible, the Israeli authorities said.
The additional reinforcements come as thousands of residents fled to safety early on Friday from a wildfire burning north of Athens. Five municipalities were evacuated overnight and five people were injured.
The massive blaze, now on its fourth day, has devastated 20 kilometres of forest area, destroyed several houses and shrouded Athens in the acrid smell and smoke of the fire.
Traffic was halted on the country’s main highway connecting Athens to northern Greece, as crews tried to use the road as a barrier to stop the flames advancing before water-dropping planes resumed flights at first light. But sparks and burning pine cones carried the fire across the highway at several points.
Several firefighters and volunteers were hospitalised with burns, health officials said.
In total, nearly 60 villages and settlements were evacuated on Thursday and early Friday across southern Greece, with weather conditions expected to worsen as strong winds were predicted in much of the country.
Greek Prime Minister Kyriakos Mitsotakis said on Thursday evening that the country was facing “unprecedented conditions as several days of heatwave have turned the whole country into a powder keg.”
According to Deputy Civil Protection Minister Nikos Hardalias, 57 of the 99 fires counted on Thursday were still active in the evening, especially on the island of Evia and in the Peloponnese, in the west and east of the country, where the situation remained worrying on Friday morning.