Two people were badly injured and another was missing after a firefighting helicopter with four crew aboard crashed into the sea off Greece on Wednesday, the coastguard and fire service said.

"The Romanian pilot of the helicopter was found safe and sound by the Greek coastguard off Samos and taken to the island's hospital," a coastguard official told AFP.

But she added that "two crew members -- a Romanian and a Moldovan -- were found unconscious in the water and efforts to resuscitate them are ongoing".

The fourth crew member, a Greek, was listed as missing and a coastguard rescue operation was under way to find him. 

A fire brigade official said the helicopter "was participating in fighting a forest fire on Samos", a mountainous island in the Aegean Sea.

The coastguard sent three patrol vessels and said two other boats were involved in the rescue operation.

The fire started around two pm (1100 GMT), prompting authorities to dispatch three helicopters and five planes as well as some 50 firefighters.

But strong winds hampered their efforts as temperatures hovered around the 30 Celsius mark (86 Fahrenheit).

Greece regularly sees wildfires which last year killed three people and ravaged 130,000 hectares (1,300 square kilometres) of forest.

The Athens government this year requested support from EU partners to cope with the expected threat and 250 firefighters were deployed in the country from Bulgaria, Finland, France, Germany, Norway and Romania.