Russia makes its biggest gain since capturing Bakhmut in May as war with Ukraine is set to enter its third year.

The fall of Avdiivka is Russia’s biggest gain since capturing the city of Bakhmut in May 2023 and comes almost two years to the day since President Vladimir Putin triggered a full-scale war by ordering the invasion of Ukraine.

Russia’s Ministry of Defence on Sunday said its troops had advanced 8.6km (5.3 miles) in that part of the 1,000km (621-mile) front line, and that Russian troops were pressing forward after a deadly urban battle that has left the town an almost completely depopulated wreck.

Putin hailed the fall of Avdiivka as an important victory and congratulated Russian troops.

“The head of state congratulated Russian soldiers on this success, an important victory,” the Kremlin said in a statement on its website.

Ukraine said it had withdrawn its soldiers to save troops from being fully surrounded after months of fierce fighting. Moscow has been trying to grind down Ukrainian forces just as Kyiv ponders a major new mobilisation and President Volodymyr Zelenskyy appoints a new commander to run the war.

But Russia said some Ukrainian forces were still holed up at the Soviet-era coke plant, once one of Europe’s biggest, in Avdiivka, which is key to Russia’s aim of securing full control of the industrial Donbas region.

“Measures are being taken to completely clear the town of militants and to block Ukrainian units that have left the town and are entrenched at the Avdiivka Coke and Chemical Plant,” Russian Defence Ministry spokesman Igor Konashenkov said.

Russian state television showed blue-and-yellow Ukrainian flags being taken down in Avdiivka and Russia’s white, blue and red tricolour flag raised, including over the coke plant. There was no public comment yet by Ukrainian authorities on this.

Putin sent tens of thousands of troops into Ukraine in February 2022, triggering the full-scale war after eight years of conflict in eastern Ukraine between Ukrainian forces on the one side and pro-Russian Ukrainians and Russian proxies on the other.

Avdiivka, which is called Avdeyevka by Russians, has endured a decade of conflict. It holds particular symbolism for Russia as it was briefly taken in 2014 by Moscow-backed separatists who seized a swath of eastern Ukraine but was then recaptured by Ukrainian troops who built extensive fortifications.

Control over the city was key to Moscow’s efforts to secure full control of the industrial Donbas region. Losing Avdiivka represents a significant blow for Ukraine which has been facing growing challenges in repelling Russian forces amid great ammunition shortages and limited manpower.

Capturing Avdiivka is likely to provide a morale boost for Russia ahead of Putin’s bid for re-election next month, which he is almost certain to win.

It is also seen as another step towards securing Moscow’s hold on the regional centre of Donetsk, about 20km (12.4 miles) to the east, held by Russian and pro-Russian forces since 2014.