Ukrainian fighters were clinging to their last redoubt in Mariupol on Friday after Russian President Vladimir Putin claimed victory in the biggest battle of the war, declaring the port city "liberated" following weeks of relentless bombardment.
The United States, however, disputed Putin's claim and said it believed Ukrainian forces still held ground in the city. Putin ordered his troops to blockade a giant steel works where the Ukrainians are holding out, having refused an ultimatum to surrender or die.
Ukraine said Putin wanted to avoid a final clash with its forces in Mariupol, as he lacked troops to defeat them. But Ukrainian officials also appealed for help to evacuate civilians and wounded soldiers.
In a televised meeting at the Kremlin, Putin congratulated his defence minister and Russian troops for the "combat effort to liberate Mariupol" and said it was unnecessary to storm the industrial zone containing the Azovstal steel plant.
"There's no need to climb into these catacombs and crawl underground through these industrial facilities ... Block off this industrial area so that not even a fly can get through," Putin said.
Mariupol, a major port in Ukraine's eastern Donbas region, sits between areas held by Russian separatists and Crimea, the Black Sea peninsula Moscow seized in 2014. Capturing the city would allow Russia to link the two areas.
Even as Putin claims his first big prize since his forces were driven away from the capital Kyiv and northern Ukraine last month, it falls short of the unambiguous victory Moscow has sought after months of combat in a city reduced to rubble.
In a late-night address, Ukraine's President Volodymyr Zelenskiy said Russia was doing all it could "to talk about at least some victories", including mobilising new battalion tactical groups.
"They can only postpone the inevitable - the time when the invaders will have to leave our territory, including from Mariupol, a city that continues to resist Russia regardless of what the occupiers say," Zelenskiy said.
The steel complex is one of the biggest metallurgical facilities in Europe, covering 11 sq km with huge buildings, underground bunkers and tunnels.
British military intelligence said a full Russian assault on the plant would likely mean heavy Russian casualties and Putin's decision to blockade it would free up forces for elsewhere in the east.
Russia stepped up its attacks in east Ukraine this week and made long-distance strikes at other targets including Kyiv and the western city of Lviv.
Ukraine's general staff said Russian forces had increased attacks along the whole front line in the east and were trying to mount an offensive in the Kharkiv region in the northeast.
British military intelligence also reported heavy fighting in the east as Russian forces tried to advance on settlements but said they were suffering from losses sustained early in the war and were sending equipment back to Russia for repair.
Russia calls its invasion a "special military operation" to demilitarise and "denazify" Ukraine. Kyiv and its Western allies reject that as a false pretext for a war that has killed thousands and uprooted a quarter of Ukraine's population.
The United States authorized another $800 million in military aid for Ukraine on Thursday, including heavy artillery and newly disclosed "Ghost" drones that are destroyed after they attack their targets.
"We're in a critical window now of time where they're going to set the stage for the next phase of this war," U.S. President Joe Biden said.
Asked about Putin's victory declaration in Mariupol, State Department spokesman Ned Price said it was "yet more disinformation from their well-worn playbook".
Mariupol, once home to 400,000 people, has seen not only the most intense battle of the war that started when Russian forces invaded on Feb. 24, but also its worst humanitarian catastrophe.
Ukraine estimates tens of thousands of civilians have died there. The United Nations and Red Cross say the civilian toll is at least in the thousands.
Journalists who reached Mariupol during the siege found streets littered with corpses, nearly all buildings destroyed, and residents huddled in cellars, venturing out to cook scraps or bury bodies in gardens.
Mariupol's mayor, Vadym Boichenko, told Reuters that Putin alone could decide the fate of the 100,000 civilians trapped in the city.
"The lives that are still there, they are in the hands of just one person - Vladimir Putin. And all the deaths that will happen after now will be on his hands too," Boichenko said in an interview.
Ukrainian Deputy Prime Minister Iryna Vereshchuk said 1,000 civilians and 500 wounded soldiers needed to be brought out from the plant immediately, blaming Russian forces for the failure to establish a safe corridor that she said had been agreed.
Russia says it has taken in 140,000 civilians from Mariupol in humanitarian evacuations. Ukraine says some were deported by force, in what would constitute a war crime.
BIDEN ANNOUNCES $800 MILLION MORE MILITARY AID FOR UKRAINE 
