Two crew members were killed and two others were rescued after two firefighting helicopters collided while battling a wildfire in western Attica on Sunday, according to Greek authorities and public broadcaster ERT.

The Greek Fire Service said the helicopters were taking part in efforts to contain the wildfire in the Psatha area when they collided midair and crashed, prompting an immediate search and rescue operation.

The fire service later said all four crew members had been located. Two were rescued alive, while the other two were recovered unconscious.

A Greek and a Danish crew member died in the crash, while the survivors were a Greek and a British national, it said.

The two survivors were taken to the 251st General Air Force Hospital in Athens.

The fire service said the helicopters were leased Bell aircraft, each carrying a two-member crew consisting of a foreign pilot and a Greek coordinator.

The pilot of one helicopter earlier contacted the Fire Department's operations center after the crash and reported that the copilot had been injured.

The two-member crew of that helicopter was found with minor injuries and was able to communicate with rescuers immediately after the crash.

The helicopters had taken off from Elefsina Air Base.

The fire service said the exact cause and circumstances of the collision were under investigation. (AA)