The United Nations Security Council is expected to discuss the escalating fighting in the breakaway region of Nagorno-Karabakh later Tuesday.
The closed door meeting was requested by five European nations -- Britain, Belgium, Estonia, France and Germany -- as the fighting intensified Monday between forces of Armenia and Azerbaijan in the enclave.
A spokesman for U.N. Secretary-General Antonio Guterres spoke to both President Ilham Aliyev of Azerbaijan and Armenian Prime Minister Nikol Pashinian and called for “an immediate stop to the fighting, a de-escalation of tension and a return to meaningful negotiations without preconditions or delay,” according to the Associated Press.
Officials in Nagorno-Karabakh say 58 soldiers have been killed since Sunday, when it says Azerbaijan launched an air and artillery attack.
The region also reported two civilian deaths. There was no official information about any Azeri military casualties.
Both sides exchanged accusations of using heavy artillery. The Azeri defense ministry said Armenian forces were shelling the town of Tartar.
The fighting has prompted fears that regional powers Russia and Turkey could be drawn into the violence. Moscow has a defense alliance with Armenia, while Ankara backs Azerbaijan.
Kremlin spokesman Dmitry Peskov called Monday for hostilities to immediately end and said the situation “is a cause for concern for Moscow and other countries.”
Turkish President Recep Tayyip Erdogan said Armenia’s immediate withdrawal from the region was the only way to ensure peace.
The United States called Sunday for the hostilities to end. State Department spokeswoman Morgan Ortagus issued a statement saying the U.S. “condemns in the strongest terms this escalation of violence.” The statement urged both sides to work with the OSCE Minsk Group co-chairs “to return to substantive negotiations as soon as possible.”
The OSCE Minsk Group is tasked with finding a peaceful solution to the conflict. The OSCE is the Organization for Security and Cooperation in Europe.
The U.S., along with France and Russia, co-chair the OSCE Minsk Group, which issued a joint statement Sunday concerning the “large scale military actions along the Line of Contact in the Nagorno-Karabakh conflict zone.”
“We strongly condemn the use of force and regret the senseless loss of life, including civilians,” the co-chairs said. They appealed “to the sides to cease hostilities immediately and to resume negotiations to find a sustainable resolution of the conflict.”
They called on the parties in conflict to take “necessary measures to stabilize the situation on the ground,” adding that there is no alternative to a peaceful negotiated solution of the conflict.”
Armenia and Azerbaijan declared martial law and troop mobilizations on Sunday amid fighting over Nagorno-Karabakh, a disputed, primarily ethnic Armenian enclave in Azerbaijan.
Armenia accused Azerbaijan of attacks on civilian settlements in the disputed region.
"Our response will be proportionate, and the military-political leadership of Azerbaijan bears full responsibility for the situation," the Armenian Defense Ministry said in a statement.
The ministry also said its troops shot down two Azerbaijani military helicopters and three drones after Baku’s forces began bombing the breakaway enclave, including its capital, Stepanakert.
Azerbaijan's Defense Ministry said it had launched a military operation along the "Line of Contact" between the two countries, “to suppress Armenia's combat activity and ensure the safety of the population."
The ministry confirmed the downing of only one Azerbaijani helicopter and said its crew had survived.
Armenian separatists seized Nagorno-Karabakh from Azerbaijan in a bloody war in the 1990s that killed an estimated 30,000 people.
Talks to resolve the conflict have been halted since a 1994 cease-fire agreement among Armenia, Azerbaijan and Nagorno-Karabakh.
Peace efforts in the Nagorno-Karabakh conflict, mediated by the Minsk Group, collapsed in 2010.