Hundreds of firefighters were battling to contain wildfires at different locations on the Greek island of Chios for a third day on Tuesday after the island declared a state of emergency.

Some 444 firefighters assisted by eight aircraft have been deployed to the island in the northeastern Aegean Sea to tackle the fires that have torn through swathes of forest and agricultural land and forced hundreds of villagers to evacuate in recent days.

Chios is in the midst of the tourist season and authorities also want to prevent the fires reaching areas famous for producing mastiha, a natural resin harvested from mastic trees.

Authorities issued a new alert on Tuesday, advising residents of a seaside village southwest of Chios town, the island's capital, to leave as white smoke rose over a nearby beach. Livestream from Greece's public broadcaster showed a helicopter spraying water over the area.

"A lot of work is still needed to bring the wildfires under control," a Greek fire brigade official who requested anonymity told Reuters. Northerly winds were complicating firefighting efforts, they added.

Greece, Europe's southernmost tip, is often hit by wildfires during its hot and dry summers but authorities have blamed a fast-changing climate for fuelling more destructive blazes in recent years.

Athens has paid out hundreds of millions of euros in damages related to extreme weather to households and farmers and to update firefighting equipment.

It has a record 18,000 firefighters this year in anticipation of a challenging fire season.