A state of emergency has been declared on the Greek island of Evia where wildfires have led to the evacuation of several villages.
The blaze broke out yesterday in the densely forested island east of Athens.
Italy is sending two aircraft after an appeal for airborne firefighting equipment from Greek authorities.
Officials said the conditions were improving after firefighters spent the night battling flames, which were fanned by strong winds and high temperatures.
Kostas Bakoyannis, the regional governor for central Greece, told Skai TV: "The situation appears better. There was a huge effort (to contain the fire), superhuman efforts."
Water dumping by specially equipped aircraft started at first light.
"It is a difficult fire, that's the reality ... there is no danger to human life and that is what is important," Mr Bakoyannis said.
Fire officials said four villages and hundreds of people were evacuated as a precaution yesterday.
Christos Stylianides, the European Union's Aid Commissioner, said: "The situation in Evia was very difficult and remains difficult."
Drawing upon his experience from other forest fires around Europe, Mr Stylianides said he was impressed at the coordination shown among authorities dealing with the emergency, calling firefighters "heroes".
Michalis Chrysohoidis, EU Civil Protection Minister, said: "We managed to protect lives and to save people's property."
Greece has bitter memories of a horrific blaze that tore through the seaside town of Mati near Athens in July 2018, killing 102 people in a matter of hours.
Irishman Brian O'Callaghan-Westropp, who was on honeymoon with his wife Zoe Holohan, was among those who died.
Authorities were accused then of poor coordination and a slow response.
Prime Minister Kyriakos Mitsotakis interrupted his holiday on Crete to return to Athens where he was briefed on the situation.
Parts of Evia's forests are a Natura 2000 site, which the EU designates as a nature reserve.
Greece often faces wildfires during its dry summer months and authorities have warned of the high risk of blazes this week.
Environmental campaigners see an increasing number of wildfires around the world as a symptom of climate change.