Moscow: Armenian and Azerbaijani officials on Thursday said that they had finalised a draft peace agreement to end nearly four decades of conflict between the South Caucasus countries, a sudden breakthrough in a fitful and often bitter peace process.

Armenia and Azerbaijan have fought a series of wars since the late 1980s, when Nagorno-Karabakh, a region in Azerbaijan that had a mostly Armenian population at the time, broke away from Baku with Yerevan's support.

"The peace agreement is ready for signing. The Republic of Armenia is ready to start consultations with the Republic of Azerbaijan on the date and place of signing the agreement," Armenia's Foreign Ministry said in a statement.

In its statement, Azerbaijan's Foreign Ministry said: "We note with satisfaction that the negotiations on the text of the draft Agreement on Peace and the Establishment of Interstate Relations between Azerbaijan and Armenia have been concluded."

However, the timeline for signing the deal is uncertain as Azerbaijan has said a prerequisite for its signature is a change to Armenia's constitution, which it says makes implicit claims to its territory. Armenia denies such claims, but Prime Minister Nikol Pashinyan has repeatedly said in recent months that the country's founding document needs to be replaced and has called for a referendum to do so. No date has been set.

The outbreak of hostilities in the late 1980s prompted mass expulsions of hundreds of thousands of mostly Muslim Azeris from Armenia and Armenians, who are majority Christian, from Azerbaijan.

Peace talks began after Azerbaijan retook Karabakh by force in September 2023, prompting almost all of the territory's 100,000 Armenians to flee to Armenia. Both sides had said they wanted to sign a treaty to end the long-running conflict, but progress has been slow and relations tense.

Their 1000 km (621 miles) shared border is closed and heavily militarised. Armenian Prime Minister Nikol Pashinyan said that Armenia and Azerbaijan will not deploy third-country forces along their border after the two sides sign a peace agreement.

The European Union has a monitoring mission in Armenia, whose mandate it has extended until February 2027.