It was not immediately clear how long the ceasefire, which began at midday local time, would last and how effective it would be. There were reports from both sides of continued fighting in the run-up, and the two countries also alleged serious breaches after it got underway.

The Moscow ceasefire talks were the first diplomatic contact between the two sides since fighting over the mountainous enclave erupted on Sept. 27, killing hundreds of people. The enclave is internationally-recognised as part of Azerbaijan but is populated and governed by ethnic Armenians.

Russian Foreign Minister Sergei Lavrov, who helped mediate between the two sides, said in a statement in the early hours of Saturday after more than 10 hours of negotiations that the ceasefire had been agreed on humanitarian grounds.

The International Committee of the Red Cross would help make the truce work, he said.

“The specific terms of the ceasefire still need to be agreed,” said Lavrov, who said Armenia and Azerbaijan had also agreed to enter into what he called substantive peace talks.

Those talks would be held under the auspices of the Organization for Security and Co-operation in Europe’s (OSCE) Minsk Group, he said.

Armenian Foreign Minister Zohrab Mnatsakanyan and his Azeri counterpart Jeyhun Bayramov did not speak to reporters in Moscow after striking the ceasefire deal.

But Mnatsakanyan later paid tribute on Armenian state TV to Russian President Vladimir Putin, whom he said had played a key role in making sure the talks happened and had personally intervened to help get an agreement.

Turkey, which has strongly backed Baku, welcomed the deal but said much more was needed.

“The humanitarian ceasefire is a significant first step but will not stand for a lasting solution,” the Turkish foreign ministry said in a statement.

“Turkey emphasized that it will support any solution approved by Azerbaijan. Turkey will continue to stand by Azerbaijan in the field and at the table”.

The Azeri defense ministry in a statement accused ethnic Armenian forces of shelling populated areas on Saturday morning ahead of the ceasefire, an allegation Yerevan denied.

Armenia’s defense ministry, which said forces in the enclave had been ordered to halt fighting from midday, in turn accused the Azeris of using attack drones on a populated settlement inside Armenia and said it looked like Baku was trying to change the facts on the ground before the truce took hold.

Ethnic Armenian officials in Nagorno-Karabakh also accused the Azeris of firing missiles at Stepanakert, the biggest town in the region, but said there was no data on casualties yet.

Baku denied shelling or using drones against civilian areas.

Nagorno-Karabakh officials said that 28 members of their defense forces had been killed in fighting since Friday.

Renewed fighting in the decades-old conflict has raised fears of a wider war drawing in Turkey, a close ally of Azerbaijan, and Russia, which has a defense pact with Armenia.

The clashes have also increased concern about the security of pipelines that carry Azeri oil and gas to Europe.

The fighting is the worst since a 1991-94 war that killed about 30,000 people and ended with a ceasefire that has been violated repeatedly.