Azerbaijani forces have taken control of a strategic city in the separatist territory of Nagorno-Karabakh and are nearing its capital, a spokesman for the region’s government confirmed, and Azerbaijan said it shot down a Russian helicopter over Armenia far from the fighting, killing two Russian servicemen.

The seizure of Shushi — which Azerbaijani President Ilham Aliyev had claimed a day earlier — is the most significant military development since fighting between Azerbaijani and Armenian forces over Nagorno-Karabakh restarted in September.

Azerbaijan said its forces shot down the Russian military helicopter as it flew over Armenia. The incident happened about 45 miles away from Nagorno-Karabakh, but Azerbaijan said the war there was a contributing factor.

Nagorno-Karabakh lies in Azerbaijan but has been under control of ethnic Armenian forces backed by Armenia.

President Ilham Aliyev
President Ilham Aliyev (Vugar Amrullaev/Azerbaijani Presidential Press Office/AP)

Shushi’s position six miles from the regional capital of Stepanakert gives strategic advantage to whoever holds it. The city is on the main road connecting Stepanakert with Armenia. Long queues of vehicles jammed the territory’s main road on Sunday as Nagorno-Karabakh residents fled the fighting into Armenia.

“Unfortunately, we are forced to admit that a series of failures still haunt us, and the city of Shushi is completely out of our control,” said Vagram Pogosian, a spokesman for the president of the government in Nagorno-Karabakh. “The enemy is on the outskirts of Stepanakert.”

Armenian Prime Minister Nikol Pashinian insisted “the fight for Shushi is continuing”, indicating Armenian forces were trying to retake the city or prevent advances toward the capital.

The Russian helicopter was downed near the border with Nakhcivan, an exclave of Azerbaijan surrounded by Armenia, Turkey and Iran.

Russia’s Defence Ministry said the helicopter was accompanying a military convoy, but did not say what the purpose of the convoy was. Russia maintains a large military base in northern Armenia, about 90 miles from the site where the helicopter was downed.

A statement from Azerbaijan’s Foreign Ministry said the helicopter was flying in the dark at low altitude and, “in the context of these factors and in light of the tense situation in the region and increased combat readiness in connection with possible provocations of the Armenian side, the duty combat crew decided to open fire to kill”.

Nagorno-Karabakh was an autonomous republic during the Soviet era. There were clashes and then full-scale war after the Soviet collapse in 1991. An estimated 30,000 people died in the fighting, which ended with a 1994 truce.

International mediation efforts by the Organisation for Security and Co-operation in Europe’s Minsk Group to determine the region’s final status have since faltered, and the region was separated from the rest of Azerbaijan by a demilitarized zone.

Mr Aliyev on Monday urged Joe Biden to intensify mediation efforts. In a congratulatory letter to the president-elect on his election victory, Mr Aliev said: “Azerbaijan expects the United States and other OSCE Minsk Group co-chairs to step up their efforts to find a just solution to the conflict.”

The current fighting has continued despite the declaration of several ceasefires. Armenia says more than 1,200 Armenian troops have been killed in the war. Azerbaijan has not stated its losses.