Two crew members have been killed after two helicopters collided mid-air in Greece as they were battling wildfires, local authorities say.

The two fatalities were a Danish pilot and a Greek fire service liaison officer. A British pilot and another Greek coordinator on the second helicopter survived.

Video of the incident some 65 km (42 miles) west of the capital Athens, shows one of the Bell helicopters hitting the propellers of the other, which bursts into flames. Both fell into a ravine.

Several fires have broken out in Greece this week, prompting mass evacuations. Several other European nations have suffered devastating wildfires after a succession of prolonged heatwaves.

According to the Greek Fire Service, the two leased Bell helicopters collided while taking part in efforts to tackle a large wildfire burning on the Attica-Boeotia border.

The crew members of one aircraft were rescued alive, while the second crew were recovered unconscious and later pronounced dead.

Greek Prime Minister Kyriakos Mitsotakis expressed his "deepest sorrow" over the accident.

In a post on X, he said the loss of the Greek coordinator and Danish pilot "fills us all with grief". He also sent condolences to their families.

According to protocol, all Bell helicopters across the country have been grounded, a source from the Ministry of Civil Protection told the BBC.

The source added that the second Bell helicopter involved in the collision made an emergency landing in an area of low vegetation.

"The two people on board, a British pilot and a Greek fire service liaison officer – escaped with minor injuries," the source said.

"Both remained conscious and have been admitted to hospital, where they will remain under observation for 24 hours as a precaution."

Erickson Air-Crane and Chinook helicopters, as well as Canadair water-bombing aircraft are continuing to carry out firefighting efforts.

Early this week, France and Spain battled huge fires - two of the main ones were close to Madrid and Bordeaux respectively. Those have now been contained, though they are still burning. Some 300,000 people who were evacuated have started to return to their homes.

In Greece, media reports describe "a titanic battle" along a swathe of territory that includes Porto Germeno, Psatha, Fokida, Megara and Kefalonia, where more than 500 firefighters have been struggling to bring the situation under control over the past 72 hours.

Most wildfires are sparked by people, whether intentionally or accidentally, but climate change is making the conditions for them more common.

Last winter was mild and wet, encouraging vegetation growth, which has then dried out in successive hot spells, generating fuel for wildfires.