Armenian and Azerbaijani troops exchange fire
Oskanyan has demanded an immediate restoration of the peace. Azerbaijan denies accusations that it's the aggressor.
A war between the countries broke out in the early 90s, claiming more than 35,000 lives.
In a referendum in 1991 Nagorno-Karabakh declared independence but it was not recognised by any country. Though de facto independent, it remains part of Azerbaijan.
In May 1994 an unofficial ceasefire, mediated by Russia, was agreed between the two countries.
According to the Armenian Defence Ministry Azeri forces are using heavy artillery to shell the Armenian positions in the disputed territory. One Armenian has been killed and several others are injured. According to the Azerbaijan side two people are dead.
The Armenian Foreign Ministry accuses Azeri forces of violating the ceasefire agreement, but shots are fired almost every other day and casualties are not uncommon. However this incident has on a different scale as heavy artillery has been used, as well as encroachment into Armenian territory being registered.
The Azeris insist that the shooting is continuing. They also accuse the Armenians of deflecting attention from recent riots in the Armenian capital when eight people died during one night. They accuse the Armenians of looking for an external enemy.