Britain has accused President Vladimir Putin of deliberate disinformation after he claimed the UK was supplying Ukraine with "weapons with a nuclear component".
Following talks in Moscow with China's President Xi Jinping, Mr Putin said Russia will "respond accordingly" if Britain sends depleted uranium tank ammunition to the government in Kyiv.
The Ministry of Defence (MOD), however, dismissed the warning, saying the armour-piercing shells had been standard equipment for decades and were "nothing to do with nuclear weapons or capabilities".
At a news conference alongside Mr Xi, the Russian leader pointed to British plans to send the Ukrainians depleted uranium shells along with a squadron of Challenger 2 main battle tanks.
"It looks like the West indeed intends to fight Russia until the last Ukrainian," he said.
"If that happens, Russia will respond accordingly, given that the collective West is starting to use weapons with a nuclear component."
He did not elaborate on what the response might be.
In response, an MOD spokesman said: "Alongside our granting of a squadron of Challenger 2 main battle tanks to Ukraine, we will be providing ammunition, including armour-piercing rounds which contain depleted uranium.
"Such rounds are highly effective in defeating modern tanks and armoured vehicles.
"The British Army has used depleted uranium in its armour-piercing shells for decades. It is a standard component and has nothing to do with nuclear weapons or capabilities.
"Russia knows this, but is deliberately trying to disinform."
The spokesman added that independent research by scientists from groups such as the Royal Society had assessed that any impact to personal health and the environment from the use of depleted uranium munitions was "likely to be low".