A British soldier fighting alongside Ukrainian marines in the city of Mariupol said his unit has "no choice but to surrender".
Aiden Aslin, 27, contacted his family in the early hours claiming the unit had run out of food and ammunition.
The former care worker from from Newark, Nottinghamshire, had been fighting with the 39th Brigade Ukrainian Marines.
He had posted videos of the fight against Russian forces since the start of the invasion of Ukraine.
After weeks of battling enemy forces, he has reportedly told a friend: "It's been 48 days.
"We tried our best to defend Mariupol but we have no choice but to surrender to Russian forces.
"We have no food and no ammunition. It's been a pleasure everyone, I hope this war ends soon."
Aiden previously said he was praying for the West to help end the "endless civilian bombings" leaving hundreds of innocent Ukrainians dead, reports the Sun.
It comes as Ukrainian marines say they are surrounded by Russian soldiers in the besieged city of Mariupol.
The 36th marine brigade of the Ukrainian armed forces said it is now relying on cooks, drivers and other non-combat troops to fight Putin's soldiers.
It comes as Kyiv estimated that tens of thousands of people had been killed in the Russian attack on Mariupol.
Much of the city has been devastated by Russian bombs, including the Mariupol theatre, where hundreds of people were killed.
The 36th marine brigade of the Ukrainian armed forces wrote on Facebook : "Today will probably be the last battle, as the ammunition is running out.
"It's death for some of us, and captivity for the rest."
Commenting on the destruction in the city, President Voloymyr Zelensky said: "Mariupol has been destroyed, there are tens of thousands of dead, but even despite this, the Russians are not stopping their offensive."
At least 300 people taking shelter at a theatre in Mariupol were killed by a Russian airstrike as Vladimir Putin's war rages.
