Fighting between Armenian and Azerbaijan forces over the breakaway region of Nagorno-Karabakh continued on Monday morning with the deployment of heavy artillery on both sides, they said.
The Armenian defence ministry reported fighting throughout the night, while Azerbaijan’s defence ministry said Armenian forces were shelling the town of Terter.
The clashes between the two former Soviet republics, which fought a war in the 1990s, are the latest flare-up of a long-running conflict over Nagorno-Karabakh.
Nagorno-Karabakh said dozens of its servicemen had been killed and more than 100 wounded after Azerbaijan launched an air and artillery attack early on Sunday. Armenia and Nagorno-Karabakh declared martial law and mobilised the male population.
Azerbaijan, which also declared martial law, said its forces responded to Armenian shelling and that five members of one family had been killed by Armenian shelling.
It also said its forces had seized control of up to seven villages. Nagorno-Karabakh initially denied that but later acknowledged losing “some positions” and said it had suffered a number of civilian casualties, without giving details.
The clashes prompted a flurry of diplomacy to reduce the new tensions in a decades-old conflict between majority Christian Armenia and mainly Muslim Azerbaijan, with Russia calling for an immediate ceasefire and another regional power, Turkey, saying it would support Azerbaijan.
President Donald Trump has said the United States would seek to end the violence.
The U.S. State Department condemned the violence in a statement, calling for an immediate halt to hostilities and any rhetoric or other actions that could worsen matters.
U.S. Democratic presidential nominee and former Vice President Joe Biden said in a statement that hostilities could escalate into a wider conflict and urged the Trump administration to push for more observers along the ceasefire line and for Russia “to stop cynically providing arms to both sides.”
Pipelines shipping Caspian oil and natural gas from Azerbaijan to the world pass close to Nagorno-Karabakh. Armenia also warned about security risks in the South Caucasus in July after Azerbaijan threatened to attack Armenia‘s nuclear power plant as possible retaliation.
Nagorno-Karabakh broke away from Azerbaijan in a conflict that broke out as the Soviet Union collapsed in 1991.
Although a ceasefire was agreed in 1994, after thousands of people were killed and many more displaced, Azerbaijan and Armenia frequently accuse each other of attacks around Nagorno-Karabakh and along the separate Azeri-Armenian frontier.