Russian President Vladimir Putin stressed the need for strict observance of a ceasefire agreement between Armenia and Azerbaijan during a phone call with Armenian Prime Minister Nikol Pashinyan, the Kremlin said on Friday.
The call was held late on Thursday at Armenia's request after its defence ministry accused Azerbaijan of moving forces into its territory and Armenia's prosecutor general opened a criminal case into "an infringement of territorial integrity".
Azerbaijan dismissed the accusations, saying it was enforcing its own border. Armenia said on Thursday it had stopped the Azeri advance and that Azeri troops had returned to their positions. There were no reports of casualties.
Russia brokered a ceasefire last year that ended a bloody conflict between Azeri and ethnic Armenian forces over the Nagorno-Karabakh enclave that locked in territorial gains for Azerbaijan.
During the phone call, Pashinyan told Putin he had decided to appeal to the Collective Security Treaty Organisation (CSTO), a six-member military alliance that is led by Russia and includes Armenia, over the infringement, the TASS news agency cited the Armenian cabinet as saying.
"Pashinyan spoke in favour of constructive dialogue and cooperation, with the aim of solving all problems that arise through peaceful, political and diplomatic means," the Kremlin said in a statement.
The Kremlin said Russia was determined to continue mediation efforts and maintain close contacts with both Yerevan and Baku.