Seven Azeri soldiers and a civilian and four Armenian servicemen were killed on Tuesday in the third day of border clashes between countries that fought a war in the 1990s over the mountainous Nagorno-Karabakh region.

The international community worries about clashes between Armenia and Azerbaijan in part because of the threat to instability in the South Caucasus, a region that serves as a corridor for pipelines taking oil and gas to world markets.

Both countries said exchanges of fire that began on Sunday had continued into Tuesday, and each accused the other of ceasefire violations and shelling.

An army major-general and a colonel were among seven Azeri servicemen killed, Azeri deputy defence minister Kerem Veliyev said, adding: “Devastating blows were inflicted on the enemy”.

Armenia’s Defence Ministry said four of its servicemen, including a major and a captain, had been killed in skirmishes. Foreign Ministry spokeswoman Anna Naghdalyan said the city of Berd had been shelled near the border but Armenian forces had “destroyed the Azeri bases” that fired on it.