Rishi Sunak's spokesperson has responded after Vladimir Putin warned that Western involvement in the conflict risked provoking a nuclear war.
The Russian president's remarks followed a suggestion this week that sending NATO troops to Ukraine could not be ruled out.
"[Western nations] must realise that we also have weapons that can hit targets on their territory. All this really threatens a conflict with the use of nuclear weapons," Mr Putin said.
A Number 10 spokesperson said they hadn't seen his specific comments but the UK remained "fully supportive" of Ukraine.
A "small number" of UK personnel are in the country providing diplomatic security and helping train Ukraine's forces, they said.
There are no plans for a "large-scale" deployment of UK troops to Ukraine, the prime minister's spokesperson said earlier this week.
