The Russian army on Saturday reported a violation of the cease-fire deal that ended the conflict between Azerbaijan and Armenia in November over the region of Nagorno-Karabakh, while both sides accused each other.

"One case of cease-fire violation was reported on Dec. 11 in the Hadrut district," said a statement from the Russian Defense Ministry, which has deployed peacekeepers to the region.

The Armenian army reported attacks from Azerbaijan on two villages that are under the control of Karabakh forces.

The Azerbaijani Defense Ministry said "adequate countermeasures" had been taken against "provocations" from the other side but added that the truce was "currently being respected."

Four Azerbaijani servicemen were killed when their units were attacked in areas adjacent to the Nagorno-Karabakh region, Azerbaijani Defense Ministry said on Sunday in another statement.

A spokesperson for the Russian peacekeeping forces confirmed "exchanges of fire with automatic weapons," telling the Ria Novosti press agency that requests to respect the cease-fire had been sent to both parties.

The new clashes mark the first significant breach of the peace deal brokered by Russia on Nov. 10 that saw Azerbaijan reclaim control over large parts of Nagorno-Karabakh and surrounding lands which were occupied by Armenian forces for more than a quarter-century.

Azerbaijani President Ilham Aliyev reacted on Saturday by blaming Armenia for the new clashes and threatened to "break its head with an iron fist."

"Armenia shouldn't try to start it all over again," Aliyev said during a meeting with top diplomats from the U.S. and France who have tried to mediate the conflict that has spanned decades.

"It must be very cautious and not plan any military action. This time, we will fully destroy them. It mustn't be a secret to anyone."

Azerbaijan's president also said that the Organization for Security and Co-operation in Europe (OSCE) Minsk Group has yet to play a role in resolving the Nagorno-Karabakh conflict which recently escalated after Armenian forces launched attacks on Azerbaijani civilians and security personnel.

Aliyev's remarks came amid an OSCE Minsk group meeting held in the capital Baku with the participation of the group's co-chairs France's Stephane Visconti and Andrew Schofer from the U.S., along with the Personal Representative of the OSCE Chairperson-in-Office Andrzej Kasprzyk.

Aliyev said the status-quo in the region has changed and the Azerbaijani leadership resolved the decades-long conflict through force and diplomatic means.

Although the OSCE Minsk Group proposed ideas to resolve the dispute, they did not bear fruit, according to the president.

Azerbaijan solved the problem on its own, Aliyev also said, adding that his country managed to beat Armenia on the battlefield.

The president further noted that Baku does not have an issue with the Armenian population living in the region, underlining that their standard of living will improve under Azerbaijani rule.

Nagorno-Karabakh lies within Azerbaijan but was under the occupation of Armenian forces since a separatist war there ended in 1994. That war left Nagorno-Karabakh itself and substantial surrounding territory in Armenian hands.

In 44 days of fighting that began in late September and left more than 5,600 people killed on both sides, the Azerbaijani army pushed deep into Nagorno-Karabakh, forcing Armenia to accept last month's peace deal that saw Azerbaijan reclaim much of the separatist region along with surrounding areas. Russia deployed nearly 2,000 peacekeepers for at least five years to monitor the peace deal and to facilitate the return of refugees.

Azerbaijan marked its victory with a military parade on Thursday that was attended by President Recep Tayyip Erdoğan and involved more than 3,000 troops, dozens of military vehicles, and a flyby of combat aircraft.

The peace deal was a major shock for Armenians, triggering protests calling for the resignation of Prime Minister Nikola Pashinian, who has refused to step down. He described the peace agreement as a bitter but necessary move that prevented Azerbaijan from taking over all of Nagorno-Karabakh.

On the visit to Azeri capital Baku, Erdoğan hailed what he dubbed his close ally's "glorious victory" in the conflict.

Erdoğan warned, however, that "Azerbaijan's saving its lands from occupation does not mean that the struggle is over."

Turkey’s Defense Ministry on Sunday also stated in a weekly briefing that the efforts for the establishment of a joint center between Ankara and Moscow to monitor the implementation of the Karabakh deal are still ongoing.