By Guy Faulconbridge and Tom Balmforth
MOSCOW/KYIV (Reuters) -Russia on Sunday said it had full control of the Ukrainian town of Avdiivka after Ukrainian troops withdrew, though Moscow said that some were still holed up in a Soviet-era coke plant after one of the most intense battles of the war.
The fall of Avdiivka is Russia's biggest gain since it captured 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 defence ministry said its troops had advanced about 9 km (5 miles) in that part of the 1,000-km (620-mile) front line, and that Russian troops were pressing forward after an deadly urban battle.
Ukraine said it had withdrawn its soldiers to save troops from being fully surrounded after months of fierce fighting. Putin hailed the fall of Avdiivka as an important victory and congratulated Russian troops.
Ukrainian authorities said they had opened an investigation into alleged shootings by Russian forces of six unarmed Ukrainian soldiers in Avdiivka, and two at a village in the same region.
Russia's defence ministry did not respond to a Reuters email sent outside regular business hours seeking comment on the allegations.
After the failure of Ukraine to pierce Russian lines last year, Moscow has been trying to grind down Ukrainian forces just as Kyiv ponders a major new mobilisation and President Volodymyr Zelenskiy appoints a new commander to run the war.
"The head of state congratulated Russian soldiers on this success, an important victory," the Kremlin said in a statement.
FULL CONTROL
But Russia said some Ukrainian forces were still holed up at the 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.
There was no public comment by Ukrainian authorities. 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.
Russia cast the Ukrainian withdrawal as rushed and chaotic, with some soldiers and weapons left behind. The Ukrainian military said there had been casualties but that the situation had stabilised somewhat after the retreat.
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 swathe of eastern Ukraine but was then recaptured by Ukrainian troops who built extensive fortifications.
WEAPONS SHORTAGES
U.S. President Joe Biden had warned that Avdiivka could fall to Russian forces because of ammunition shortages following months of Republican congressional opposition to a new U.S. military aid package for Kyiv.
A White House statement said Biden called Zelenskiy on Saturday to underscore the U.S. commitment to continue supporting Ukraine, and he reiterated the need for Congress to urgently pass the package.
The White House said the withdrawal had been forced upon Ukraine "by dwindling supplies as a result of congressional inaction," that had forced Ukrainian soldiers to ration ammunition and resulted in Russia’s first notable gains in months.
Zelenskiy urged allies at a global security conference in Munich on Saturday to plug a shortage of weapons and said stalled U.S. aid was imperative. He praised his troops for "exhausting" Russian forces in Avdiivka, and suggested the withdrawal was partly caused by a lack of weapons.
"Now, (the military) will replenish, they will wait for the relevant weapons, of which there simply weren't enough, simply aren't enough," he said. "Russia has long-range weapons, while we simply don't have enough."
BOOST FOR RUSSIA
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 20 km (12 miles) to the east, held by Russian and pro-Russian forces since 2014.
Neither Russia nor Ukraine have given details of their losses in the war or in the intense battle for Avdiivka. Western intelligence assessments say hundreds of thousands of men on both sides have been killed or wounded in the war.
Putin congratulated the Russian commander in charge of the assault on Avdiivka, Colonel-General Andrei Mordvichev.
"Eternal glory to the heroes who fell in fulfilling the tasks of the special military operation!" Putin said in a telegram.
Ukrainian Defence Minister Rustem Umerov said Avdiivka showed the need for modern air defence systems to counter guided bombs and long-range weapons to destroy enemy formations. He said artillery shells were also needed.
Colonel-General Oleksandr Syrskyi, who took command of the Ukrainian military in a shake-up last week, said Ukrainian forces had moved back to more secure positions outside the town "to avoid encirclement and preserve the lives and health of servicemen".
Ukraine's 3rd Assault Brigade, which officials say was deployed to Avdiivka this week, said on Telegram it had pulled back to prepared positions on the outskirts of Avdiivka and evened out the front line.
"At this time, the Russians are not slowing down their assault. We keep holding the line in the area of Avdiivka," it said.
Separately, Ukrainian forces repelled a Russian offensive on the southern front in the area of Zaporizhzhia, the Ukrainian military said on Sunday.
There was no comment on that yet from the Russian side.