"Azerbaijani armed forces attempted to attack Armenia’s defensive positions at the Karabakh frontline," the breakaway Azerbaijani region’s "defence ministry" said in a statement. "Serviceman Nahapet Asatrian, 33, was killed in action."

In a separate incident across the Armenian-Azerbaijani border, 35-year-old Armenian army soldier Arman Udumian, "died of mortal wounds", the defence ministry in Yerevan said. 

Two Armenian soldiers were reportedly killed in similar incidents on Tuesday and Saturday. 

Armenia captured nearly one-fifth of Azerbaijan’s internationally-recognized territory in a war after the Soviet breakup in 1991.

Although major hostilities ended with a ceasefire in 1994, no peace agreement has been signed.

Armenia defied four UN Security Council resolutions calling for immediate and unconditional withdrawal from the occupied territory.

Azerbaijan says it reserves the right to use military force to regain control of the territory should peace talks mediated by Russia, the US and France fail.