Three Armenian troops died in border clashes with Azerbaijani forces on Wednesday, Yerevan said, in the deadliest military incident between the arch-foes since their war last year over the disputed Nagorno-Karabakh region.
"As a result of armed action launched following an attack by Azerbaijani forces, there are three dead and two wounded from the Armenian side as of 08:30 (0430 GMT)," the defence ministry in Yerevan said.
It said an intense shootout took place near the village of Sotk at the north-eastern sector of the border shared by the Caucasus neighbours.
Armenia's foreign ministry said that "the Azerbaijani side is deliberately escalating the situation as its forces remain illegally on Armenia's sovereign territory."
Azerbaijan's defence ministry accused Armenia of a military provocation, saying "two Azerbaijani servicemen were wounded" after Armenian forces opened fire towards Azerbaijani positions in the district of Kelbajar, in the early hours of Wednesday.
"Armenia bears full responsibility for the escalation of tensions along the two countries' shared border," it said.
Tensions between Baku and Yerevan have been running high since May, when Armenia accused Azerbaijan's military of crossing its southern frontier to "lay siege" to a lake shared by the two countries.
The six-week war between Armenia and Azerbajan last autumn claimed about 6,500 lives and ended in November with a Russian-brokered ceasefire under which Armenia ceded territories it had controlled for decades.
Both countries have reported occasional shootouts in recent months along their shared border, sparking fears of a flare up in the territorial dispute.
Ethnic Armenian separatists in Nagorno-Karabakh broke away from Azerbaijan as the Soviet Union collapsed, and the ensuing conflict has claimed around 30,000 lives.