The six-week armed conflict for control of the disputed Nagorno-Karabakh region claimed more than 6,500 lives and ended last November with a Russian-brokered truce.

Under the ceasefire agreement, Armenia ceded swathes of territories it had controlled for decades.

On Tuesday, Azerbaijan's defence ministry said "Armenia's armed forces committed a large-scale provocation at the state border at 11:00 am (GMT 0700) on Tuesday."

"Armenian troops attacked Azerbaijani positions in the districts of Kelbajar and Lachin," the ministry said in a statement, adding that two Azerbaijani troops were wounded in the clashes.

Azerbaijani troops "stopped the enemy's advance, surrounded and detained Armenian servicemen," it added.

Armenia's defence ministry, for its part, said Azerbaijani forces "attempted to break through the Armenia's state border, at the eastern direction" before being repelled by Armenian troops.

It said that four Armenian soldiers were wounded and noted that "Azerbaijani armed forces are using artillery and weapons of various calibres."

Armenia appealed to ally Russia for military support in protecting its territorial integrity, according to their military pact.

"Given that there was an attack on Armenia's sovereign territory, we appeal to the Russian Federation... to protect Armenia's territorial integrity," said Security Council Secretary Armen Grigoryan.

Both Armenia and Azerbaijan said the situation along their border remained tense with clashes ongoing on Tuesday afternoon.

Since last year's war, both countries have reported occasional exchanges of fire along their shared border, sparking fears of another flare up in their territorial dispute.

On Sunday, they traded accusations of opening fire at their border near Karabakh.

On Saturday, Nagorno-Karabakh authorities said the only road connecting Armenia to the separatist enclave -- the Lachin Corridor -- was briefly closed due to an incident between the two sides.

Ethnic Armenian separatists in Nagorno-Karabakh broke away from Azerbaijan as the Soviet Union collapsed in 1991, and the ensuing conflict claimed around 30,000 lives.