One of the fire fronts on Tuesday stretched more than eight kilometres, according to witnesses and officials, burning homes and cars around the area of Mandra, west of the capital, which was blanketed by dense smoke.
"We are living a nightmare," Mandra mayor Christos Stathis told Open TV.Â
"Houses and properties are on fire."
In 2017, Mandra, a largely industrial area, was hit by flash floods that killed 24 people.
Traffic was suspended for hours on two national roads connecting Athens with the cities of Elefsina and Corinth, where oil refineries operate. Late on Tuesday, the flames were headed toward the seaside town of Nea Peramos.
Homes and a small shipyard in the town of Neos Pontos had been destroyed. Earlier a thick column of smoke rose into the sky after an explosion, a Reuters witness said.
At least seven districts have been evacuated and police assisted the evacuation of more than 300 people, a police official told Reuters.
The blaze, which broke out on Monday in the region of Dervenochoria, about 30km north of Athens, spread fast as it was fanned by erratic winds and reached Mandra on Tuesday, forcing people to flee and burning houses.
Efforts to extinguish the fire continued through the night with more than 250 firefighters backed by volunteers and 75 fire engines.
Another fire, in the area of Corinth, was also burning uncontrolled. At least 30 houses were severely damaged by that fire, which broke out on Monday, the deputy governor of the Corinth region said.
Greece has called for help from its European Union partners. Italy and France have sent four Canadair water bomber aircraft and foreign firefighters are also helping fight the blazes.
Recently re-elected Prime Minister Kyriakos Mitsotakis cut short his trip to Brussels, where he had been attending an EU-Latin America summit, earlier on Tuesday, to return home and monitor more closely the operation.
Firefighters managed to contain other blazes southeast and west of the Greek capital, but some fronts were still active and flames were rekindled by strong winds.
A fire which broke out on Monday in the village of Kouvaras, about 30km southeast of the Greek capital had been tamed. Fanned by strong winds it had quickly spread to the coastal towns of Anavyssos, Lagonisi and Saronida.
The Greek meteorological service has warned of a high risk of fire this week, just as the country is recovering from the first major heatwave of the summer. A second heatwave was forecast for later this week.
Greece has bitter memories of a wildfire disaster in 2018, when a blaze killed 101 people in the seaside town of Mati, east of Athens, in a matter of hours.
