Ukrainian troops in the besieged city of Mariupol have warned that they may be facing their “last battle” against Russia.
“Today will probably be the last battle, as the ammunition is running out,” an account belonging to the 36th marine brigade said on Facebook.
“It’s death for some of us and captivity for the rest,” it said.
Ukraine’s President Volodymyr Zelensky said that tens of thousands of people had likely been killed in Mariupol.
The BBC has not verified the figure, but reports from the region and the refugees fleeing the city spoke of bodies lying in the streets and most buildings damaged or destroyed.
Mariupol lies between the pro-Russia breakaway regions of Donetsk and Luhansk in the east, and annexed Crimea in the south. Seizing the city has been a major goal of the Russian offensive, and it has been battered by bombs for weeks amid a fierce Ukrainian resistance.
Mr Zelensky said Mariupol had been “burned to ashes”.
The 36th marine brigade, in its post, warned that after 47 days of defending the city, the unit had been surrounded by the Russian army, and was facing “hand-to-hand combat”.
But the post promised Ukrainians its soldiers “did everything possible and impossible” to stop the Russian advance.
“The mountain of wounded makes up almost half of the brigade. Those whose limbs are not torn off return to battle,” it said.
“The infantry was all killed and the shooting battles are now conducted by artillerymen, anti-aircraft gunners, radio operators, drivers and cooks. Even the orchestra.”
It also complained about a lack of support from other parts of the Ukrainian military, with aid promised which never came.
The post said the marines have been pushed back to the Azovmash factory in the city. It is believed there is also fighting inside the Azovstal industrial zone, which is on the coast.
Some experts have expressed scepticism about the post, suggesting that the Facebook page could have been hacked by Russian operatives. But others are sure that it is authentic.
Russian state media claim that some Ukrainian troops have begun to surrender, though such claims cannot be verified.
Mariupol has seen little let-up in the fighting since the war began, with little humanitarian aid, long delays to evacuations, and reports of civilians starving or being forcibly removed to Russia-held territory.
The head of pro-Russia Donetsk separatists, Denis Pushilin, told Russian media that he thought more than 5,000 people may have been killed, though he blamed Ukrainian forces.
Russian forces have continued to slowly advance and seize more of the city in recent weeks – unlike in the rest of Ukraine, where they have “refocused” military action around the breakaway regions in the east, largely pulling out of other areas such as near the capital, Kyiv.
As a result, Ukrainian officials are focusing on evacuating civilians from eastern towns and cities in anticipation of a renewed assault in some places.
Nine new humanitarian corridors have been agreed between Ukraine and Russia, to allow civilians to flee, including from Mariupol.
Ukraine is also putting on extra trains to extract people from the Donetsk and Luhansk regions, where Russia is focusing its efforts.
Mr Zelensky said that tens of thousands of pro-Russian troops are believed to have redeployed and massed in the area, and a renewed offensive is widely expected to come soon.
