YEREVAN (Armenia): Armenia’s Defense Ministry said Wednesday that three of its troops were killed and two more were wounded in clashes with Azerbaijani forces on the border between the two ex-Soviet nations, which have been locked in a decades-long tug-of-war over the Nagorno-Karabakh region.

Azerbaijan’s Defense Ministry said two of its servicemen were wounded Wednesday.

Both countries have accused each other of starting the clashes. Azerbaijan said Armenian forces opened fire at its positions on the Kalbajar section of the border. The Armenian military said its personnel were attacked by Azerbaijani forces.

Armenia’s Foreign Ministry issued a statement saying that “the Azerbaijani side has been deliberately initiating escalation,” and the Foreign Ministry in Azerbaijan said in turn that “the responsibility for aggravating the situation by committing another provocation on the Armenian-Azerbaijani border lies entirely with the military-political leadership of Armenia.”

Tensions on the border have been simmering since May, when Armenia protested what it described as an incursion by Azerbaijani troops into its territory. Azerbaijan has insisted that its soldiers were deployed to what it considers its territory in areas where the border has yet to be demarcated.

In the wake of the clashes on Wednesday, Azerbaijan’s Foreign Ministry urged Armenia “to stop military provocations and start negotiations on the delimitation of the two state borders.”

Armenia’s Foreign Ministry vowed to “use all its military-political tools in accordance with international law” in response “to the use of force by Azerbaijan against the territorial integrity of Armenia.”

Later Wednesday, the two nations agreed to cease the hostilities on the border in a move proposed by Russia. Moscow brokered a peace deal last November to end six weeks of fighting over Nagorno-Karabakh, a region that lies within Azerbaijan but was under the control of ethnic Armenian forces backed by Armenia since a separatist war there ended in 1994.

More than 6,000 people were killed in the conflict. The Russia-brokered truce allowed Azerbaijan to reclaim control over large parts of Nagorno-Karabakh and surrounding areas, which Armenia-backed separatists controlled for more than 25 years.

The United Nations urged both sides “to exercise restraint, refrain from any action that could escalate tensions, and address related concerns through dialogue,” U.N. deputy spokesman Farhan Haq said, expressing “growing concern” at continued reports of tensions on the Armenian-Azerbaijan border.