More than 250 Russian servicemen, including dozens of officers, were captured during Operation Vivaldi, an offensive in northern Donetsk.
Many surrendered as entire units after Ukrainian drones cut off their food, water and ammunition.
A commander in Ukraine’s 3rd Army Corps, the unit central to the operation, told The Telegraph that Russian soldiers had been warned they would be tortured and killed if captured.
“They were reluctant to surrender because they were afraid, and they were blowing themselves up, trying to take our soldiers with them,” Olexander Borodin said.
“The Russian army has this propaganda preaching that if they go into Ukrainian captivity, they will be tortured; they will be killed.”
The offensive has resulted in the killing of 3,000 Russian soldiers in a matter of months, and the recovery of 48 square miles of occupied territory, according to the 3rd Army Corps.
Fought in three stages so far, it has relied on drones and robots advancing before infantry, including kamikaze ground vehicles air-dropped behind Russian lines.
The Russians who did surrender have revealed dire conditions during their time in Donetsk, including being forced to drink their own urine and eat tree bark and nettles.
They told the 3rd Army Corps that injured soldiers were not evacuated from their positions and that their only chance of survival was to crawl to an evacuation point on their own.
One of the Russian officers told the corps that his soldiers were dying en masse from exhaustion and starvation.
“Some lost 30 or 40 kilos from their normal weight, and many of them were asking just for one thing, like a sip of water,” said Mr Borodin.
“They were not even thinking about their further situation. All they wanted was just a sip of water.”
Ukrainian commander Olexander Borodin says Russian soldiers had been told they would be tortured and killed if captured
He said about half of the prisoners needed medical treatment, many of them for wounds they had been trying to treat themselves while holding their positions.
Russian commanders knew about the conditions but did little to improve them, Mr Borodin claimed, and did not try to evacuate the wounded because it would put pressure on the army’s medical service.
The corps said Ukrainian strikes on Russian supply routes and command posts drove the surrenders, with drones destroying logistics lines and positions cut off by mines dropped from above.
The 3rd Army Corps said the mass detainments resulted in some of the highest numbers of senior officials being detained in the war to date.
Ukraine hopes to use the prisoners, particularly the officers, to secure the release of Azov fighters held in Russia since autumn 2022.
Mr Borodin said there’s “more chance” Moscow will exchange captured Ukrainians for higher-ranked officers “than a random Russian soldier”.
Many of the prisoners also described corruption within their own units.
Some told Mr Borodin their commanders had ordered them to hand over part of their salaries to buy equipment, which never arrived.
“Some of them feel betrayed by their command,” he said.
That sense of betrayal has left many reluctant to go home. Although Ukraine hopes to trade them for its own soldiers, Mr Borodin said a large number of the prisoners did not want to be exchanged.
Russian soldiers who have been captured are seen by their own army as lesser fighters, he said, and the men feared being sent straight back to the front line in even worse conditions than before.
“Russians consider those who went into captivity to be something like worse soldiers, like second-best,” he said. “They are afraid that they would be sent in a much, much worse condition, and they want to remain in Ukrainian captivity for as long as they can.”
