Greek firefighters said Wednesday that they hope to bring a forest fire blazing near Athens under control "in the coming hours".

-The situation has improved and we hope to bring the fire under control in the coming hours- the fire service said in a statement.

More than 500 firefighters, a dozen water-bombing planes and five helicopters have been battling the blazes outside the capital since Tuesday afternoon.

Around a dozen houses have been destroyed in the flames, and dozens of businesses, bars and holiday accommodation have been severely damaged in Varympompi, 30 kilometres (20 miles) northwest of Athens, officials said.

Villages have been evacuated and part of a major motorway linking the capital with the north and south of the country was cut for safety reasons.

With the country reeling under a severe heatwave, the blaze spread at the foot of Mount Parnith, sending thick smoke over the capital.

Local media reported dozens of children had been rescued from a holiday camp near the Athens suburb of Varympompi.

-We are facing a difficult fire in extreme heatwave conditions- said Prime Minister Kyriakos Mitsotakis who went to Varympompi during the morning.

Deputy minister for civil protection Nikos Hardalias told reporters that after "an exceptionally difficult night", with four fire fronts, "there is only one left now".

Experts have warned climate change is increasing both the frequency and intensity of the wildfires.

Several other blazes were still raging Wednesday in Greece, notably in the southern Peloponnese region, 300 kilometres from the capital, three villages were evacuated after a fire started Tuesday afternoon.

Another was blazing on the island of Euboea, some 200 kilometres east of the capital where eight villages were evacuated.

More than 3,000 hectares (7,400 acres) of pine and olive were burned out by a fire that erupted Saturday near the city of Patras, 200 kilometres (125 miles) west of Athens. It was brought under control on Monday.

Turkey is suffering its worst fires in at least a decade, claiming the lives of eight people and forcing hundreds to evacuate in southern areas popular with tourists.