Officials say at least four soldiers were killed and several others wounded in a border clash between Armenian and Azerbaijani forces early on December 29.
Armenia's Defense Ministry said three of its servicemen were killed and several wounded in a shoot-out prompted by what it described as an infiltration attempt by Azerbaijani troops at the northeastern section of the border between the two South Caucasus countries.
Azerbaijan's Defense Ministry said one of its troops was killed in fighting.
Armenian Defense Ministry spokesman Artsrun Hovannisian wrote on Facebook that sniper rifles and grenade launchers were used in fighting near the Armenian village of Chinari.
Azerbaijan and Armenia have been locked in a conflict over Azerbaijan's breakaway region of Nagorno-Karabakh for years.
Nagorno-Karabakh, populated mainly by ethnic Armenians, declared independence from Azerbaijan during a 1988-94 war that claimed an estimated 30,000 lives and displaced hundreds of thousands of people.
In April, a truce halted four days of fierce fighting in and around Nagorno-Karabakh between Armenia-backed separatists and Azerbaijan's military.
About 75 soldiers were killed in the worst fighting seen in the region since the fragile 1994 cease-fire.
With reporting by AP