BAKU/YEREVAN (Reuters) - Armenia's Defense Ministry accused Azerbaijan's armed forces on Wednesday of shooting down a military helicopter belonging to Nagorno-Karabakh, a region in Azerbaijan which is controlled by ethnic Armenians.
The downing of the helicopter, the first such incident since a ceasefire was agreed in 1994 after a war over the tiny mountainous territory in the South Caucasus, ratcheted up tensions between Armenia and oil-producing Azerbaijan.
Three crew were on board the helicopter, which was on a training flight, Defense Ministry officials in Nagorno-Karabakh and Armenia said.
Azerbaijan confirmed it had shot down a helicopter but said it was an Armenian aircraft which had intended to attack Azeri soldiers near the mined and heavily guarded line of contact around Nagorno-Karabakh.
"The enemy's aviation, after a series of maneuvers, attempted to attack Azeri positions," the Azeri Defense Ministry said in a statement.
Officials in Azerbaijan and Nagorno-Karabakh said crew members were believed to have been killed in the incident, although they added that the information was not confirmed.
The Azeri defense ministry said an army officer had been honored for shooting down the aircraft. The officer "has been awarded a third degree medal 'For Distinguished Military Service' for shooting down the enemy's Mi-24 helicopter, and for vigilance and heroism on combat duty," the ministry said.
The attack drew threats of retaliation from Armenia.
"Consequences for this unprecedented aggravation of the situation will be very painful for the Azeri side," Armenian Defense Minister Artsrun Hovhannisyan said on his Facebook page.
The violence highlights the risk of tensions over Nagorno-Karabakh triggering a wider conflict in the South Caucasus, where oil and natural gas flow from the Caspian region to Europe.
About 30,000 people were killed in 1991 in fighting between ethnic Azeris and Armenians which erupted as the Soviet Union collapsed.
Despite the 20-year ceasefire, mainly Muslim Azerbaijan and predominantly Christian Armenia regularly trade accusations of inciting violence around Nagorno-Karabakh and along the Azeri-Armenian border, where clashes also occur.
Nagorno-Karabakh runs its own affairs with heavy military and financial backing from Armenia. Armenian-backed forces also run seven Azeri districts surrounding Nagorno-Karabakh seized during the war.
Efforts to reach a permanent settlement of the conflict have failed despite mediation attempts led by France, Russia and the United States.
Writing by Margarita Antidze; Editing by Dominic Evans