One of the world’s oldest conflicts, a territorial dispute between Armenia and Azerbaijan, has re-erupted with the heaviest clashes in years.
At least 23 people were reported to have been killed on Sunday as the two ex-Soviet republics battled over the Nagorno-Karabakh region.
The region is internationally recognised as part of Azerbaijan but controlled by ethnic Armenians.
When it broke away in the early 1990s, tens of thousands died in fighting.
Azerbaijani President Ilham Aliyev said on Sunday he was confident of regaining control over the region.
Martial law has been declared amid the violence in some parts of Azerbaijan, as well as in Armenia and Nagorno-Karabakh.
The conflict in the Caucasus Mountains has remained unresolved for more than three decades, with periodic bouts of fighting.
Border clashes in July killed at least 16 people, prompting the largest demonstration in years in the Azerbaijani capital Baku, where there were calls for the region’s recapture.
Any upsurge in violence could unsettle markets as the South Caucasus is a corridor for pipelines carrying oil and natural gas from the Caspian Sea to world markets.
Turkish President Recep Tayyip Erdogan pledged support for Azerbaijan, urging the world to stand with the country in its “battle against invasion and cruelty”. Azerbaijanis are a predominantly Turkic people with whom Turkey has close ties.