Hundreds of firefighters in Greece on Saturday were battling to save a popular coastal resort northwest of Athens as violent winds continued to lash the country, hampering operations.

The fire department said over 300 firefighters were operating in the area of Porto Germeno, some 70 kilometres (45 miles) northwest of Athens in the region of Viotia.

"The fire has reached the sea... homes have certainly been damaged," a fire department spokesman told AFP.

"The winds are very strong. Aircraft are trying to operate as best they can, but some are unable to and have been transferred to another fire (in the Peloponnese) where conditions are milder," he added.

The fire broke out Friday near the neighbouring coastal village of Agios Vasileios. Residents initially ignored a civil protection call to evacuate, and some 300 people had to be rescued by sea.

Theodore Giannaros, a wildfire meteorologist and senior researcher at the National Observatory of Athens on Saturday said the damage to the Porto Germeno area was "inconceivable".

"The area that has been affected appears to exceed 4-5,000 hectares," he said in a Facebook post.

Wildfires have flared in several parts of the country this week, including on the popular island of Crete, and three firefighters have so far lost their lives.

On Friday, another fire threatened the suburb of Haidari west of Athens that had to be partly evacuated.

A maximum fire risk alert has been issued for Saturday in the greater Athens area, parts of the Peloponnese and Crete, central Greece and the border region with Turkey.

Greece's geography, with its hundreds of islands, complicates the rapid deployment of emergency responders.

Hit hard by the climate crisis like the rest of the Mediterranean region, the country is plagued by wildfires every summer due to high temperatures, frequent heat waves, and drought.

Greek Prime Minister Kyriakos Mitsotakis warned on Thursday that Greece -- which had been relatively spared from heat waves and major fires earlier this summer, unlike France and Spain -- was headed for "difficult days".