A forest blaze in Greece is "the largest wildfire ever recorded in the EU" and the bloc is mobilising nearly half its firefighting air wing to tackle it, a European Commission spokesman said Tuesday.

Firefighters have been battling the flames for 11 days in northeastern Greece which have killed at least 20 people and pose an "ecological disaster".

Eleven planes and one helicopter from the EU fleet have been sent to help Greece counter the fire, north of the city of Alexandroupoli, along with 407 firefighters, spokesman Balazs Ujvari said.

The EU's civil protection service said the fire has burnt over 810 square kilometres (310 square miles) – an area bigger than New York City.​

"This wildfire is the largest in the EU since 2000, when the European Forest Fire Information System (EFFIS) began recording data," the service said.

Since it began on August 19, the bodies of 20 people have been found, 18 of them migrants including two children that were discovered in a region often used as an entry point from neighbouring Turkey.​

Greece's fire service told AFP that the blaze was "still out of control" in the northeast region's Dadia National Park, a major sanctuary for birds of prey.

​A large fire previously hit the park in 2011, forest ranger Dora Skartsis said, lamenting that "everything that was regenerated since has been lost" in recent days.

"We're talking about a huge ecological disaster. The image is tragic," said Skartsis, who also heads a biodiversity protection group in the region.

The forest also plays a vital economic role in supporting logging, beekeeping and tourism activities in Evros, one of the poorest regions of the country.

In Alexandroupoli alone, at least 4,000 sheep and goats have been killed in the blaze and warehouses containing animal feed destroyed, according to Kostas Dounakis, who heads the local cattle breeders' association.

Deadly impact

The European Union currently calls on a fleet of 28 aircraft – 24 water-dumping planes and four helicopters – supplied by member countries to help battle blazes in the bloc and in nearby neighbours.

It is working on creating a standalone, EU-funded air wing of 12 aircraft that will be fully in place by 2030.

​"We do know that fires are getting more severe," Ujvari noted.

"If you look at the figures every year in the past years, we are seeing trends which are not necessarily favourable, and that calls for, of course, more capacities at the member states' level.

Greece has been ravaged by numerous fires this summer which the government attributes to climate change.

The EU air deployment "underscores our commitment to swift and effective collective action in times of crisis," the EU's commissioner for crisis management, Janez Lenarcic, said.

Looking beyond the fire season, Greek Prime Minister Kyriakos Mitsotakis met several ministries on Tuesday to discuss the necessary reforestation of the region once the blaze is extinguished.

Environment Minister Theodoros Skylakakis also announced that work must begin on flood prevention to prevent landslides along the now barren terrain when rains return in the autumn.​

© Agence France-Presse