De facto authorities in the breakaway region of Nagorno Karabakh say four ethnic Armenian soldiers were killed early on June 28 by Azerbaijani fire.
Azerbajian's Defense Ministry said in a statement that its positions were fired upon from Nagorno-Karabakh and one Azerbaijani soldier was wounded.
The ministry did not comment on the Nagorno-Karabakh authorities' claim that four of their soldiers had been killed by Azerbaijani fire.
Moscow is "concerned over the increasingly frequent armed incidents and cease-fire violations in Nagorno-Karabakh," Russian Foreign Ministry spokeswoman Maria Zakharova said.
"We call for restraint and for the settling of all vexed questions by peaceful, political-diplomatic means -- in cooperation with the leadership of the Russian peacekeeping contingent," she added.
The reported incident comes as the United States on June 27 opened three days of peace talks between Armenia's and Azerbaijan's foreign ministers in Washington in the latest effort to quell a conflict that has flared repeatedly.
On June 27, U.S. State Department spokesman Matthew Miller said Washington was encouraged by recent efforts by the two countries to pursue a peace agreement.
SEE ALSO: Iran's Relations With Azerbaijan Get Heated Over Attacks, Baku's Ties To Israel"We continue to believe that peace is within reach and direct dialogue is the key to resolving the remaining issues and reaching a durable and dignified peace," Miller said ahead of the talks.
Miller added that the discussions involving Armenian Foreign Minister Ararat Mirzoian and Azerbaijani Foreign Minister Jeyhun Bayramov would cover "very sensitive" areas.
U.S. Secretary of State Antony Blinken opened the closed-door talks, the second negotiations involving the South Caucasus adversaries in two months.
SEE ALSO: For The Ethnic Armenian Leadership In Nagorno-Karabakh, The Walls Are Closing InRussia, which has traditionally been heavily involved in mediating the two sides' longstanding conflict over Nagorno-Karabakh, currently has peacekeeping troops on the ground to monitor the Moscow-brokered cease-fire that ended six weeks of deadly fighting in November 2020.
The brief conflict, which left more than 2,000 soldiers dead on each side, resulted in Baku regaining control over part of Nagorno-Karabakh that had been occupied by Armenian forces since the end of the first Nagorno-Karabakh war in 1994.
Armenia has repeatedly said that Russian peacekeepers are failing to live up to its promises to protect ethnic Armenians in the mountainous region, which is internationally recognized as Azerbaijan's territory but is predominantly populated by ethnic Armenians.
In May, Armenian Prime Minister Nikol Pashinian said any recognition by Yerevan of Nagorno-Karabakh as part of Azerbaijan would be dependent on guaranteeing the rights and security of the some 100,000 ethnic Armenians who live there.
Russia has pressed Azerbaijan to allow unhindered traffic through the Lachin Corridor linking the territory to Armenia in keeping with the cease-fire.
Russian Foreign Ministry spokeswoman Maria Zakharova said in a statement on June 23 that the entrance to the corridor had been blocked by Azerbaijan in a move she said increased tensions at a time when Baku and Yerevan are trying to work out a peace treaty.
There have been reports that the corridor has been blocked since June 15. But Baku has insisted that civilians and aid convoys are allowed access to the route, despite concerns expressed by the International Red Cross that the blockage of aid convoys could cause food and medicine shortages.
Baku, which set up a checkpoint along the corridor following months of disruption despite the cease-fire calling for all routes to be unblocked, has said that Azerbaijani activists protesting alleged illegal mining were responsible for any blockages.