Armenian and Azerbaijani defense officials said heavy clashes continued overnight and reported further civilian deaths, after Russian President Vladimir Putin announced the meeting in Moscow late Thursday and appealed for a cease-fire on humanitarian grounds, AFP reported.

Azerbaijan’s President Ilham Aliyev has repeatedly said there would be no halt to fighting until Armenian troops withdraw and vowed to continue the intervention until his military captured all of Karabakh.

Renewed fighting over Karabakh – an ethnic Armenian region of Azerbaijan that broke from Baku’s control in a devastating war in the early 1990s – has claimed some 400 lives and forced thousands of people from their homes.

The heavy clashes erupted late last month, with both sides blaming the other for the biggest outbreak in violence since a 1994 cease-fire left the status of Karabakh in limbo.

The region’s declaration of independence has not been recognized by any country – even Armenia – and the international community regards it as part of Azerbaijan.

The Kremlin said late on Thursday that following a series of calls with Armenian Prime Minister Nikol Pashinyan and Aliyev, Putin had invited their foreign ministers to Moscow and called for an end to hostilities “in order to exchange dead bodies and prisoners”.

Previous diplomatic efforts to find a lasting solution to the decades-old stalemate have faltered.

Putin’s announcement of talks in Moscow came shortly after international mediators from France, Russia and the United States launched their first efforts to resolve the fighting in Geneva.

The countries make up the “Minsk Group” that has sought a solution to the Karabakh conflict for decades but have failed to stop sporadic outbreaks of fighting.

The negotiations in Geneva went ahead without Armenia, which refused to participate if the fighting was ongoing, and there were no public statements following the closed-door talks.

Mounting civilian toll

Pashinyan on Friday said his country was “ready for the resumption of the peace process”, while Russian Prime Minister Mikhail Mishustin during a visit to Yerevan said Russia was prepared to help bring about peace.

Since the fighting restarted, both sides have accused the other of shelling areas populated by civilians and thousands of people have been displaced by the clashes.

The administrative center of the disputed region, Stepanakert, is dotted with wide craters and unexploded ordnance following days of shelling.

Armenia accused Azerbaijan on Thursday of hitting the iconic Ghazanchetsots (Holy Savior) Cathedral leaving a gaping hole in its roof and several journalists injured.

Armenia’s rights ombudsman Artak Beglaryan said this week that the renewed fighting has displaced around half of Karabakh’s 140,000 residents and forced some 90 percent of its women and children from their homes.

Dozens of civilians have been confirmed killed and the Armenian side has acknowledged 350 military deaths, while Azerbaijan has not admitted to any fatalities among its troops.

“Iran is closely monitoring the alarming violence in Nagorno-Karabakh,” Zarif tweeted on Sunday.

“We call for an immediate end to hostilities and urge dialogue to resolve differences.

“Our neighbors are our priority and we are ready to provide good offices to enable talks.

“Our region needs peace now.”

According to reports coming from the region, clashes erupted between Azerbaijan and Armenia on Sunday over the volatile Nagorno-Karabakh region, reigniting concern about instability in the South Caucasus, a corridor for pipelines transporting oil and gas to world markets.

Both sides, which fought a war in the 1990s, reported fatalities. Armenia and Nagorno-Karabakh, a breakaway region that is inside Azerbaijan but is run by ethnic Armenians, declared martial law and mobilized their male populations.

Iran called on Azerbaijan and Armenia to exercise restraint and engage in negotiations.

“The Islamic Republic of Iran is closely monitoring military conflicts between the Republic of Azerbaijan and the Republic of Armenia with concern, and while inviting both parties to show self-restraint, calls for immediate cessation of clashes and initiation of talks between the two countries,” Iranian Foreign Ministry spokesman Saeed Khatibzadeh said on Sunday.

He added that Tehran is ready to employ all its capacities to help establish a cease-fire and start peace talks between the two sides.

Nagorno-Karabakh broke away from Azerbaijan in a conflict that broke out as the Soviet Union collapsed in 1991.

At least 200 people were killed in a flare of the conflict between Armenia and Azerbaijan in April 2016. There are frequent skirmishes and at least 16 were reported killed in clashes in July.