Azerbaijan said on Sunday it had established a checkpoint on the only land route to the contested region of Nagorno-Karabakh, a step that was followed by claims of border shootings by both Azeri and Armenian forces.
Nagorno-Karabakh is internationally recognised as part of Azerbaijan, but its 120,000 inhabitants are predominantly ethnic Armenians and it broke away from Baku in a war in the early 1990s.
Azerbaijan said it had established a checkpoint on the road leading to Karabakh, a step it said was essential due to what it cast as Armenia's use of the road to transport weapons.
Azerbaijan "took appropriate measures to establish control at the starting point of the road," the foreign ministry said.
"Providing border security, as well as ensuring safe traffic on the road, is the prerogative of the government of Azerbaijan, and an essential prerequisite for national security, state sovereignty and the rule of law".
Armenia said the checkpoint at the Hakari bridge in the Lachin corridor was a gross violation of the 2020 ceasefire agreement which ended a 2020 war. It called on Russia to implement the agreement which states that the Lachin corridor, the only road across Azerbaijan that links Armenia to Nagorno-Karabakh, must be under Russian peacekeepers' control.
"We call on the Russian Federation to ultimately implement the trilateral statement," Armenia's foreign ministry said of the agreement that was brokered by Russian President Vladimir Putin.
Pictures of the bridge posted on social media by Azeri officials showed one side of it blocked by vehicles and soldiers.
Armenia's defence ministry said a soldier named Artyom Poghosyan was killed at around 0750 GMT when Azeri forces opened fire on an Armenian position in Sotk, an Armenian village east of Lake Sevan. Azerbaijan denied it killed the soldier.
Azerbaijan then claimed that Armenian soldiers fired on Azeri units at around 1110 GMT in the Lachin district, a claim Armenia denied.
In 2020, Azerbaijan retook territory in and around the enclave after a second war that ended in a Russian-brokered ceasefire upheld by Russian peacekeepers.
Azeri civilians identifying themselves as environmental activists have been facing off since 12 December with Russian peacekeepers on the Lachin corridor.
Armenia says the protesters are government-backed agitators who are effectively blockading Karabakh. Azerbaijan denies blockading the road, saying that some convoys and aid are allowed through.
In recent months Armenia has repeatedly called on Moscow to do more to support the peace and ensure unfettered access between Armenia and Nagorno-Karabakh through the Lachin Corridor.