United Nations chief Antonio Guterres on Tuesday called on Azerbaijan and Armenia to de-escalate tensions amid recent fighting which claimed lives on both sides.

"The Secretary-General is deeply concerned about reports of renewed fighting along the Armenian-Azerbaijani border," his spokesman Stephane Dujarric said on Tuesday.

Guterres urged both sides to take immediate steps to deescalate tensions, exercise maximum restraint, and resolve any outstanding issues through dialogue and within existing formats, Dujarric said.

Azerbaijan has accused Armenia of "large-scale provocations" in recent days, saying saboteurs planted mines and Armenian forces carried out “intensive” firing on Azerbaijani positions.

These actions by Armenian forces led to the confrontation, the Azerbaijani Defense Ministry said, adding that there were casualties on both sides, including 50 Azerbaijani soldiers.

Relations between the former Soviet republics of Armenia and Azerbaijan have been tense since 1991 when the Armenian military occupied Nagorno-Karabakh, also known as Upper Karabakh, a territory internationally recognized as part of Azerbaijan.

In 2020, Azerbaijan liberated several cities and over 300 settlements and villages that were occupied by Armenia, and the fighting ended with a deal brokered by Russia.