Azerbaijan has announced a unilateral cease-fire in the disputed region of Nagorno-Karabakh, where a recent flare-up of violence between Azerbaijani and separatist Armenian forces has left dozens of people dead.

Separatist forces reject Azerbaijan's claims of a cease-fire, saying they see no sign that the government has stopped fighting, the Associated Press reports.

The cease-fire announcement comes two days after a fresh wave of violence broke out in Nagorno-Karabakh, killing at least 30 Azeri and Armenian troops.

The BBC writes that civilian casualties have been reported on both sides.

A separatist war in the region in the late '80s and early '90s killed 30,000 and displaced a million people. For the last two decades, Nagorno-Karabakh has been controlled by ethnic Armenian separatists, with a cease-fire in place that has been periodically violated.

This weekend's fighting is some of the worst since that cease-fire was imposed, the BBC reports.

The cause of the renewed violence isn't clear; both sides point to the other as the source of provocation. The BBC notes that "nationalist sentiment boosted by pro-government media in both societies has been at its height in recent years."

The AP provides some background on the conflict:

"Nagorno-Karabakh, a region in Azerbaijan, has been under the control of local ethnic Armenian forces and the Armenian military since a war ended in 1994 with no resolution of the region's status. The conflict is fueled by long-simmering tensions between Christian Armenians and mostly Muslim Azeris."Armenian forces also occupy several areas outside Nagorno-Karabakh proper. The sides are separated by a demilitarized buffer zone, but small clashes have broken out frequently."

Stability in the southern Caucusus, which numerous pipelines cross through, is "a major strategic objective" for the region's oil producers, including Azerbaijan, Reuters writes:

"World top oil producer Russia — which maintains a garrison of troops, jets and attack helicopters in northern Armenia — has been a key mediator in the conflict over Nagorno-Karabakh, which is home to around 150,000 people, and moved on Saturday to suppress the renewed violence."President Vladimir Putin urged the warring sides to immediately observe the ceasefire while Russia's foreign and defence ministers talked by phone with their Armenian and Azeri counterparts."The Azeri presidential press service said Turkey, the other major power in the region along with Russia, had voiced support for [Azerbaijan's] actions, RIA reported."Copyright 2016 NPR. To see more, visit