The mid-air collision took place west of Athens, in the Psatha area, shortly after midday on Sunday.
It comes after more than 100 homes were destroyed by wildfires raging out of control, with strong winds fanning flames across Europe.
A search and rescue operation for the crews is currently under way, with Greece’s fire department confirming the collision on Sunday afternoon.
Footage of the incident, circulated online, shows the moment one helicopter’s rotor blades appear to clip the underside of the second firefighting helicopter.
WATCH:Two firefighting helicopters collided midair in Greece. https://t.co/6QK4e8zsIa pic.twitter.com/apsbt5edWj
— Open Source Intel (@Osint613) August 2, 2026
Seconds later, flames erupt from the aircraft and the fireball can be seen dropping out of the sky.
The helicopters were part of a larger firefighting operation in the region, transporting water in a bid to tackle wildfires a handful of miles outside the Greek capital.
Images emerging from the region show locals battling flames as Europe continues to be gripped by record-breaking temperatures.
According to the fire service: "Search and rescue teams were immediately mobilised to locate and assist the crews," it said.
Fire services are currently struggling to contain multiple fires around the greater Athens region, with further blazes on Cephalonia island.
Meanwhile, other areas of Europe are struggling amid soaring temperatures, with firefighters battling an extensive plaze in the Bordeaux region of France.
The rapidly spreading fires were also seen to impact areas of Spain, with hundreds of homes and thousands of hectares destroyed.
It comes as several wildfires swept the UK, with firefighters working through the night, with 10 fire appliances on the scene in Dunwich Heath, Suffolk, to support firefighting operations.

World Affairs Correspondent