The Armenian Defense Ministry says heavy fighting has broken out with Azerbaijani forces in Nagorno-Karabakh, a section of Azerbaijan that is under the control of local ethnic Armenian forces and the Armenian military.

Ministry spokesman Artsrun Hovhannisyan told The Associated Press on Saturday that the fighting was taking place along the entire "line of control" that separates Nagorno-Karabakh from the rest of Azerbaijan. In a separate posting on Facebook, he said there were losses on both sides and that an Azerbaijani helicopter was hit.

There was no immediate comment from Azerbaijan authorities.

Nagorno-Karabakh has been controlled by Armenia's military and local forces since a war ended in 1994. Years of negotiations under the Organization for Security and Cooperation in Europe have brought little progress in resolving the dispute.