Armenia, Azerbaijan and Russia signed an agreement on Tuesday to end six weeks of fierce fighting in Nagorno-Karabakh in a deal Armenian Prime Minister Nikol Pashinyan described as “unspeakably painful” in an emotional Facebook post.

The post was the first indication of a deal, with Pashinyan saying the agreement would take effect from 1am on Tuesday (21:00 GMT on Monday) to end a conflict that has left at least 1,000 people dead.

The deal was later confirmed by Azerbaijan and the Kremlin.

“The signed trilateral statement will become a (crucial) point in the settlement of the conflict,” Azerbaijan’s President Ilham Aliyev said in a televised online meeting with Russian President Vladimir Putin.

The agreement came hours after ethnic Armenian officials in the disputed region confirmed that the key city of Shusha (known as Shushi in Armenia), the second-biggest city in the enclave, had been taken by Azeri forces. Azerbaijan also said on Monday it had taken dozens more settlements.

Describing the decision as “unspeakably painful for me personally and for our people”, Pashinyan said the agreement followed “an in-depth analysis of the military situation” that has seen Azeri forces closing in on Stepanakert, the region’s main city.

He said the agreement was “the best possible solution to the current situation”.