Russia, the U.S. and France said late Monday that the escalating conflict between Armenia and Azerbaijan over the occupied Nagorno-Karabakh represented an "unacceptable threat" to the region's stability.

The three countries' foreign ministers in a joint statement condemned "in the strongest terms the unprecedented and dangerous escalation of violence," adding that attacks allegedly targeting civilian centers "constitute an unacceptable threat to the stability of the region."

"The ministers call once again upon the conflicting parties to accept an immediate and unconditional ceasefire," the statement said.

Fighting in the region broke out again on Sept. 27, when Armenian forces targeted civilian Azerbaijani settlements and military positions, leading to casualties.

Relations between the two former Soviet republics have been tense since 1991, when the Armenian military occupied Nagorno-Karabakh, an internationally recognized territory of Azerbaijan.

The Organization for Security and Co-operation in Europe (OSCE) Minsk Group, co-chaired by France, Russia and the U.S., was formed in 1992 to find a peaceful solution to the conflict, but to no avail. A cease-fire, however, was agreed upon in 1994.

Multiple United Nations resolutions, as well as many international organizations, demand the withdrawal of the invading forces.

Many world powers, including Russia, France and the U.S., have urged an immediate cease-fire following the latest flare-up in the conflict. Turkey, meanwhile, has supported Azerbaijan's right to self-defense.

Reiterating Ankara's support to Baku against recent aggression by neighboring Armenia, President Recep Tayyip Erdoğan also said Monday, "It is the duty of every honorable state to support Azerbaijan's fight to liberate its occupied territories."

The Minsk Group caused a deadlock in the dispute between the two countries, he stressed, adding that humanity cannot find permanent peace and tranquility without rescuing the world from rogue states and their rogue rulers.