Firefighters are continuing to battle wildfires in Greece as the flames reached a residential town outside the capital Athens overnight, with thousands of people being ordered to flee their homes.

There have been wildfires raging in many parts of the country over the past fortnight prompted by Greece's biggest heatwave for decades. Two people are so far known to have died.

Temperatures have been hitting 40 degrees Celsius, with strong winds making it harder for emergency services to tackle them.

The Greek fire service said Saturday that blazes were raging in the Attica peninsula that includes Athens, in Evia, the country's second largest island and located east of the capital, and the Peloponnese region in the southwest.

The fire on Mount Parnitha, on the outskirts of Athens, has forced the evacuation of thousands of people since late Thursday, and across the country, many homes, forest and farming land, animals and businesses have been destroyed.

Hundreds of firefighters - helped by reinforcements from Cyprus, France and Israel -  have been fighting the blaze north of Athens, joined by the army, and aircraft dropping water.

Prime Minister Kyriakos Mitsotakis called it a "nightmarish summer," adding the government's priority "has been, first and foremost, to protect human lives."

He said the government would reimburse people affected by the fires and would prioritize reforestation of areas burned by the fires.

Overnight on Saturday, strong winds pushed the fire into the town of Thrakomakedones, where it burned homes. Residents had been ordered to evacuate and there were no immediate reports of casualties.

Hundreds of people, including many elderly residents, were evacuated by ferry late on Friday from the town of Limni on Evian as flames reached the shore, with more being rescued on Saturday.

One of two people known to have died during the fires in Greece has been named as the president of the Athens Chamber of Commerce and Industry, Konstantinos Michalos.

He was found unconscious in a factory in Krioneri and later confirmed dead in hospital.

On Friday, a 38-year-old man from Ippokrateio, a town north of Athens, died after being hit by a falling electric pole as he rode a moped.

The blaze north of Athens closed part of a motorway linking Athens to the north of the country and migrant camps were evacuated as flames burn pine forests, blowing thick smoke across the city.

Around 5,000 tourists and residents were also forced to flee another fire in the Peloponnese region. 

The ANA news agency said two people were held on suspicion of arson, including a woman arrested in a park in Athens carrying two lighters, petrol and flammable materials, shortly after a fire broke out there.

A 43-year-old man was also arrested in the area of Krioneri near Athens and charged with arson, according to ANA.

Wildfires have hit countries across southern Europe, with Turkey battling its worst-ever wildfires, while Italy has also had to tackle wildfires amid the heatwave. North Macedonia has also declared a state of emergency.