Authorities in Greece say three navy personnel are missing after a helicopter crash in the eastern Aegean Sea.

Adm Evangelos Apostolakis, chief of Greece's armed forces, said debris from the crashed Bell 212 helicopter had been spotted Thursday off the eastern island of Leros.

Apostolakis says the crash occurred during a nighttime training exercise and that the pilots had not communicated any problem before the incident occurred. He says the search had been hampered by bad weather conditions.

Greece has a strong military presence in the eastern Aegean amid an ongoing dispute with neighbor and NATO ally Turkey over sea and airspace boundaries.