The burning of wildfires in Greece was like living in a horror movie, one resident said as she was evacuated from the Greek island of Evia by ferry on Sunday.

Thousands of people have fled their homes on Evia as wildfires burned uncontrolled for a sixth day, and ferries were on standby for more evacuations after taking many to safety by sea.

Fires that had threatened the northern suburbs of Athens in recent days died back. But the blaze on Evia, a large island north-east of the capital, quickly burgeoned into several fronts, ripping through thousands of hectares of pristine forest across its northern part, and forcing the evacuation of dozens of villages.

"(It's) like a horror movie...but this is not the movie, this is real life," said Mina, a resident, after boarding a rescue ferry in the island resort area of Pefki. "We are afraid, we feel lost, we feel abandoned, we feel alone," she added.

Wildfires have erupted in many parts of the country during a week-long heatwave - Greece's worst in three decades - with searing temperatures and hot winds creating tinder-box conditions.