The British defense ministry says Russia's defense manufacturing sector is likely using convicts in an effort to meet war-time production demands.
The ministry released on Friday its latest intelligence update on the Russian invasion of Ukraine.
It says Russia's largest tank producer told local media it would employ prisoners, and that such weapons manufacturers are almost certainly under intense pressure from Moscow to increase production.
On Wednesday, Russian President Vladimir Putin publicly conveyed his frustration to Deputy Prime Minister Denis Manturov over delays in procuring aircraft including military planes. Manturov is in charge of aviation and other high-tech industries.
During a televised video call with Cabinet ministers, Putin angrily ordered Manturov to speed up contracting new aircraft procurement, saying "do it within a month."
The US think-tank, the Institute for the Study of War, said on Thursday that "Putin likely seeks scapegoats for the Russian defense industrial base's struggle to address equipment and technological shortages." It added that Putin is also likely trying to appease domestic criticism over the lack of advanced military equipment and Russia's inability to task its industrial base to accommodate the war effort.
The Russian private military company of Wagner Group is reported to have recruited convicts from prisons to fight in Ukraine.
In Ukraine, Russian forces are stepping up their offensive on the town of Soledar in the eastern region of Donetsk, with the aim to take control of the nearby Ukrainian stronghold of Bakhmut. Ukraine said its troops were holding on in Soledar.