Josip Brozicevic, the head of the national mountain rescue service, said first responders had located the downed helicopter in the Cikola river canyon near central Croatian town of Drnis.

"The bodies of two crew members were also found," Brozicevic told AFP.

"The search for the third crew member is ongoing," he added.

Croatia's armed forces also confirmed the crash, saying it had mobilised a plane and helicopter to help survey the area where the helicopter went down.

Authorities did not give any official information about why a Hungarian military craft was flying in Croatian airspace.