Two Greek air force pilots died today when their Canadair water-bombing plane crashed while battling a forest fire on the island of Evia, the defence ministry said.
"A three-day mourning period is declared in the Armed Forces for the loss of life, in the line of duty, of the Air Force officers and pilots of the firefighting aircraft CL-215, which was operating in Evia," the Greek defence ministry said in a statement.
The national broadcaster ERT showed footage of the aircraft dropping water over a fire and then crashing into a hillside near the coastal town of Karystos before bursting into flames.
The plane was one of at least four aircraft which, along with around 100 firefighters, have been battling the blaze which broke out on Sunday.
Many regions of the country remain on "red alert", meaning that there is an extreme risk of dangerous forest fires exacerbated by strong winds.
Emergency responders are battling to contain wildfires on the island of Rhodes for a seventh day; hundreds of tourists who had been forced to flee that area in previous days are expected to fly home today.
At least 19,000 and perhaps around 20,000 people had to leave homes and hotels in Rhodes over the weekend as the inferno that began a week ago spread and reached coastal resorts on the island's southeast.
More than 2,000 holidaymakers flew home yesterday, with more repatriation flights expected today.
Tour operators also cancelled upcoming trips.
Greece is often hit by wildfires during the summer but climate change has led to more extreme heatwaves across southern Europe, raising concerns that tourists could stay away.
Hundreds of firefighters, helped by forces from Turkey and Slovakia, battled to tame the blazes close to the villages of Gennadi and Vati in the southeast of Rhodes as the wildfires resurged in hot, windy conditions
Wildfires also raged on the island of Corfu, off the west cost of Greece, and Evia island, near the capital of Athens.
"The fires have rekindled across the country but no settlements are being threatened for now," a fire brigade official said.
The Greek islands are popular with holidaymakers from around Europe in the summer.
TUI, one of the world's largest tour operators, has said it was cancelling trips to Rhodes through Friday and offering free cancellations or rebookings to other destinations.
It said it had 39,000 customers on Rhodes as of Sunday evening.
Greece has seen very high temperatures in recent weeks and the mercury was forecast to rise again through tomorrow, exceeding 44C in some areas.
Civil protection authorities warned of extreme risk of wildfires in Rhodes and on the island of Crete today.
In Athens temperatures are expected to soar to 41C, according to the national weather forecaster EMY.
Tourism accounts for 18% of Greece's output and one in five jobs. On Rhodes and many other Greek islands, reliance on tourism is even greater.
The Irish Department of Foreign Affairs is advising against travel to affected areas and said Irish citizens should fully comply with any evacuation orders in what it described as an "evolving situation".
It said anyone planning to travel to Rhodes should check with their travel operator, agency, or hotel ahead of time.
