Arch-foes Armenia and Azerbaijan accused each other on Tuesday of opening fire on their volatile border, with Yerevan saying Azerbaijani forces killed four soldiers in the southern region of Siunik.

Yerevan and Baku have fought two wars - in 2020 and in the 1990s - over the disputed Nagorno-Karabakh region, which Azerbaijan recaptured in a lightning offensive last year.

Four were killed and one injured as a result of fire on Armenian positions from Azerbaijani troops,” the Armenian defense ministry said in a statement.

The fighting occurred near the village of Nerkin Hand.

Azerbaijan’s border guards said this was a “riposte” to a “provocation” on Monday by Armenian troops that Baku said had injured one Azerbaijani soldier.

Azerbaijan’s defense ministry said Armenian troops had opened fire twice late Monday on Kokhanabi village in the Tovuz region.

Armenia denied the allegation, saying the claim that its troops had twice “fired against the direction of Azerbaijani positions situated in the northeastern part of the border, does not align with reality.”

Almost the entire ethnic-Armenian population of Karabakh - more than 100,000 people - fled for Armenia following Baku’s takeover, sparking a refugee crisis.

The border flare-up comes shortly after Azerbaijani President Ilham Aliyev was re-elected for a fifth term to steer the gas-rich Caucasus nation.

His win was expected after his country’s historic victory over Armenian separatists last year.

Aliyev is suspected of trying to wrest control over Armenia’s Siunik region to link Azerbaijan to the exclave of Nakhchivan, which is also bordered by Iran and Turkey.