Two people killed as Australian firefighting helicopters collide in Greece

Two firefighting helicopters have collided in Greece while helping to control a huge wildfire that has destroyed more than 100 homes northwest of Athens while a fresh blaze forced people to flee the popular tourist island of Kefalonia.

Two people on one helicopter - a Greek and a Danish citizen - died, while the crew on the other, one person from Greece and one from the United Kingdom, survived, the fire service said.

WATCH THE VIDEO ABOVE: Australian helicopter crashes in Greece wildfire tragedy

Investigations had started into what caused the collision, it added.

Destructive blazes in France and Spain had showed signs of easing over the weekend but several wildfires have broken out in Greece after a period of relative calm there.

The two helicopters collided in the area of Psatha in the Attica region, Greece’s fire service said in a statement.

Video posted on the Forecast Weather Greece Facebook page appeared to show two helicopters closing to cross paths at low altitude, before the main rotor of the lower helicopter struck the underside of the other.

The lower one then crashed in flames.

The second helicopter then dumped its load of water and flew away.

In a statement sent to 7News, McDemott Aviation confirmed two of their helicopters were involved in the crash.

“We are deeply saddened to confirm that the two crew members aboard one of the helicopters have lost their lives. The two crew members from the second helicopter are in the care of medical professionals,” the statement read.

“McDermott Aviation is working closely with the relevant authorities and will continue to assist as they undertake their investigation into the incident.”

Investigations suggested the fire that started in the Greek region of Boeotia before spreading to Attica was caused by sparks from conductors on a private network transmitting electricity generated by wind turbines to the main power grid, the eKathimerini website reported.

Two Greek citizens were arrested on suspicion of negligence while another suspect remains at large, the report said.

Gale-force winds that had fuelled a fire around Porto Germeno on the Gulf of Corinth 60km northwest of Athens subsided but flames crossed a mountain to the south and reached the settlement of Veniza and a military firing range, igniting unexploded ordnance.

Firefighters focused their efforts on preventing fire from advancing towards the coastal town of Megara, which has a population of about 30,000.

“There are moments when the force of nature and the intensity of weather conditions exceed all human planning and every operational capability,” Prime Minister Kyriakos Mitsotakis said in his regular Sunday message.

Greek authorities issued emergency alerts for people to leave several settlements in western Attica, including an industrial estate near Megara.

In the village of Agios Konstantinos, residents were doing their best to halt the spread of the blaze.

“The fire has been burning since last night, it is certain that they cannot have forces everywhere. We as residents are doing everything we can,” said Tasos Tzempelikos, 61, who along with his son was pouring water on the fire.

Greek daily Protothema reported that a major effort was ongoing to prevent the fire from Veniza from reaching the nearby coastal town of Megara.

It said more than 10,000 hectares of land had likely been destroyed by the fire so far.