Armenia says three soldiers have been killed by shelling from Azerbaijan, Tass agency reports, as the two neighbours accused each other of violating a ceasefire that ended two days of warfare.
Tass cited an Armenian defence ministry statement but did not give details.
Last Friday, both sides accused each other of breaching the truce by firing across the border.
After border clashes two weeks ago that killed almost 200 soldiers, the worst bout of fighting since a six-week war between the two ex-Soviet countries in late 2020, the two sides agreed to a ceasefire deal brokered by Russia.
The fighting is linked to decades-old hostilities over control of the mountainous Nagorno-Karabakh region, internationally recognised as part of Azerbaijan but until 2020 largely controlled by the majority ethnic Armenian population.
Azerbaijan's defence ministry said that at 6pm, Armenian units had started firing at Azerbaijani positions in the Kalbajar region, wounding one serviceman, and that Azerbaijani forces had taken "retaliatory measures".
The Armenian defence ministry gave an opposite account, tweeting that Azerbaijani forces had fired towards Armenian positions near the common border using mortars and large-calibre weapons, and that the Armenian side had retaliated.
Armenia said then that Azerbaijan had attacked its territory and seized settlements inside its borders; Azerbaijan said it was responding to "provocations" from the Armenian side.