“On March 25… a unit of the armed forces of Azerbaijan crossed a line of contact in the district of Shusha, in violation” of the agreement of November 9, 2020, the Russian defence ministry said in a statement on Saturday.
It added Russian peacekeepers “are taking measures aimed at preventing escalation… and mutual provocations.”
Earlier on Saturday, Azerbaijan’s defence ministry announced it has taken control of some auxiliary roads in its Armenian-majority breakaway region of Nagorno-Karabakh over which it has fought two wars with arch-foe Armenia.
The ministry added “necessary control measures were implemented by the units of the Azerbaijan Army in order to prevent the use of the dirt roads north of Lachin” for arms supplies from Armenia.
The sole road linking Karabakh to Armenia, the Lachin corridor, has been for months under Azerbaijani blockade, which Yerevan says has led to a humanitarian crisis in the enclave.
Occasional shootouts have broken out along the Armenian-Azerbaijani border and in Karabakh since a Russian-mediated truce ended six-weeks of fighting in autumn 2020.
Last week, Armenian Prime Minister Nikol Pashinyan warned against a “very high risk of escalation” in Karabakh.
Armenia has also accused Russian peacekeepers of failing to protect ethnic Armenians living in the restive region.
When the Soviet Union collapsed in 1991, ethnic Armenian separatists in Karabakh broke away from Azerbaijan. The ensuing conflict claimed some 30,000 lives.