By Alexandros Avramidis and Renee Maltezou

GRAMMATIKO, Greece/ATHENS (Reuters) – A fast-spreading forest fire fueled by gusts of wind raged unabated near Athens on Monday, burning trees, houses and cars, forcing hospitals and the evacuation of at least 11 towns and villages, Greek authorities said.

Hundreds of wildfires have broken out across Greece since May. While summer fires are common in Greece, scientists say exceptionally hot and dry weather combined with climate change has increased the frequency and intensity of the fires.

More than 560 firefighters, supported by volunteers, 17 firefighting planes and 15 helicopters fought the latest forest fire, which broke out at 3 p.m. (12 p.m. GMT) on Sunday near Varnavas, 35 kilometers north of the capital.

By Monday morning, the fire had spread southwards and was burning on several fronts, including the village of Grammatiko, the ancient city of Marathon, the coastal municipality of Nea Makri and Mount Penteli north of Athens.

Strong winds constantly changed the direction of the flames.

“Despite fierce fighting and superhuman efforts overnight, the fire spread very quickly and reached Mount Penteli,” a fire department official said.

Firefighting aircraft suspended their operations overnight and resumed early Monday. Police helped with the evacuation and some residents spent the night in emergency shelters.

At least three hospitals were evacuated in Penteli.

The fire, whose flames reached up to 25 meters high, spread “in a flash” due to stormy winds, fire department spokesman Vassilis Vathrakogiannis said on Sunday.

Thick clouds of smoke darkened the sky over Athens on Sunday evening. Hours later, flames blazed near the residential suburb of Dionysos, about 23 kilometers northeast of the city center, and in neighboring areas.

Prime Minister Kyriakos Mitsotakis has returned to Athens from a weekend holiday on the island of Crete to oversee firefighting efforts, a government official said, adding that memories of a 2018 fire that killed 104 people in the coastal town of Mati near the capital are still fresh.

After the warmest winter on record and long periods with little or no rainfall, Greece is forecast to have its hottest summer on record.

The authorities are on high fire alert until Thursday and weather experts are warning of a “very difficult week”.

“Half of Greece will be in the red,” said Vassilis Kikilias, Minister for Climate Crisis and Civil Protection, on Saturday, pointing to temperatures of around 40 degrees Celsius and strong winds.

(Reporting by Renee Maltezou and Karolina Tagaris in Athens; editing by Bernadette Baum and Mark Heinrich)