UN Secretary-General Antonio Guterres has called on the leaders of Armenia and Azerbaijan to immediately halt hostilities over the disputed region of Nagorno-Karabakh after at least 65 people were killed in the deadliest outbreak of fighting in years.
The UN chief was set to talk with Armenian Prime Minister Nikol Pashinian on September 28 after having spoken with Azerbaijani President Ilham Aliyev earlier in the day, Guterres's spokesman Stephane Dujarric said.
Guterres is also pushing the two sides to resume talks and accept the redeployment of monitors from the Organization for Security and Cooperation in Europe to the region, Dujarric said.
Meanwhile, the UN Security Council is expected to hold emergency talks on September 29 to discuss the fighting following a request from Germany and France. The fighting threatens to draw in regional powers Russia and Turkey.
Yerevan has already accused Ankara of having a "direct presence on the ground" and supplying its ally Baku with weapons, including drones.
The long-simmering conflict in the volatile South Caucasus erupted into the deadliest bouts of fighting in four years on September 27.
At least 58 Armenian servicemen and seven Azerbaijani civilians have been confirmed dead so far in the fighting. Armenian reports of losses among Azerbaijani forces have not been confirmed by Baku.
As in previous rounds of violence, both sides appear to be exaggerating the military casualties inflicted on their opponent and engaging in information warfare.
Nagorno-Karabakh has long experienced periodic border skirmishes along the so-called Line of Contact that separates Armenian and Azerbaijani forces on the front line of Europe's longest-running conflict.
In July, a days-long flare-up that included drone attacks and heavy artillery fire killed at least 17 people, mostly soldiers on both sides but including at least one civilian.
However, the latest violence appeared to be more than a flare-up, with Armenian and Azerbaijani officials describing it as war amid mutual recriminations about which side started the offensive.
"We are on the brink of a full-scale war in the South Caucasus," Armenian Prime Minister Nikol Pashinian warned, accusing Azerbaijan of carrying out preplanned aggression.
Nagorno-Karabakh is an ethnic Armenian separatist enclave inside Azerbaijan.
Armenia declared martial law and a total mobilization on September 27 in response to what it said was Azerbaijani attacks on the enclave, including in the regional capital of Stepanakert.
Azerbaijan responded by declaring a partial military mobilization on September 28
Both sides have fielded helicopters, drones, tanks, and artillery during the first two days of fighting.
The escalation of violence drew swift responses from European countries, Russia, the United Nations, the United States, and others calling for both sides to cease hostilities immediately and enter dialogue.
The European Court of Human Rights said on September 28 that the Armenian government had asked it to issue urgent instructions to Azerbaijan to stop attacks on civilians as well as military advances toward civilian settlements in Armenia and Nagorno-Karabakh.
Armenia claimed on September 28 that Azerbaijan had begun a large-scale offensive from the north on Nagorno-Karabakh as well as from he south.
Armenia's Pashinian called on global powers to prevent Turkey from interfering in the conflict amid allegations from Yerevan that the Turkish military was deepening its involvement.
In August, Turkey and Azerbaijan completed two weeks of joint air and land military exercises, including in the Azerbaijani enclave of Naxcivan. Some observers have questioned whether Turkey left behind military equipment or even a contingent of troops.
The potential for robust Turkish involvement in the conflict is being watched closely by Russia, which is already on opposing sides with the NATO member in conflicts in Libya and Syria.
Russia sells weapons to both Azerbaijan and Armenia, but has a military base in Armenia and favors that strategic partnership.
The Nagorno-Karabakh conflict emerged during the breakup of the Soviet Union, when the region and seven adjacent districts of Azerbaijan were seized by Armenian-backed separatists who declared independence amid a 1988-94 conflict that killed at least 30,000 people and displaced hundreds of thousands.
Since a fragile, Russian-brokered truce in 1994, the region has been under the control of ethnic Armenian forces that Azerbaijan says include troops supplied by Armenia.
The region's claim to independence has not been recognized by any country.