The defence ministry in Yerevan reported several hours of clashes on Saturday, including with heavy artillery, in the Hardut region of the disputed province, after Azerbaijan bolstered its military presence in the area.
"The Armenian side has six wounded," the ministry said, describing the incident as an Azerbaijani "provocation".
It added that the new fighting was discussed during a meeting in Moscow between Russian and Armenian defence ministers, while the foreign ministry said clashes continued into Sunday.
Azerbaijan on Saturday insisted that "adequate countermeasures" had been taken against "provocations" from the Armenian side.
Six weeks of fighting that erupted in September between separatists backed by Armenia and Azerbaijan over the mountainous region ended in early November with a Moscow brokered peace deal that saw the Armenians cede swathes of territory.
Russia has deployed nearly 2,000 peacekeeping troops to Nagorno-Karabakh as part of the deal and the Russian defence ministry Saturday reported the truce had been violated.
It was Russia's first report of a violation since the peace deal was introduced on November 10.
The French and American heads of the Minsk Group, which led talks on the conflict for decades but failed to achieve a lasting agreement, met with Azeri President Ilham Aliyev in Baku on Saturday.
The envoys, Stephane Visconti and Andrew Schofer, were expected in Yerevan on Sunday.
On a visit to Baku this week, Turkish President Recep Tayyip Erdogan hailed what he called his close ally's "glorious victory" in the conflict.
The Turkish leader, who attended celebrations marking Azerbaijan's success, has overtly supported Baku, helping to train and arm its military.
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