Sir Keir Starmer has said he is prepared to put “our own troops on the ground if necessary” in Ukraine if there is a deal to end the war with Russia.
Ahead of an “emergency meeting” of European leaders on Monday, the prime minister said he was “ready and willing” to put British troops into a peacekeeping force in Ukraine.
Writing in The Daily Telegraph, the prime minister also said the UK was “ready to play a leading role” in Ukraine’s defence and security, by committing £3bn a year until 2030.
It comes as Emmanuel Macron rallies the likes of Sir Keir and German Chancellor Olaf Scholz at a hastily-arranged Paris summit to discuss Ukraine’s next steps.
The French president will look to recapture Ukraine’s future at the informal meeting, which has been swiftly put together following announcements from the United States.
It will take place as the US sends senior officials to Saudi Arabia for peace talks with Russia – which representatives from Europe have not been invited to. It is unclear if Ukraine will take part.
A delegation from Ukraine is in Saudi Arabia to pave the way for a possible visit from Volodymyr Zelenskyy, one Ukrainian official said on Sunday.
However, less than 24 hours prior, a top Zelenskyy adviser had denied Ukraine would take part in the discussions.
“There is nothing on the negotiating table that would be worth discussing,” Mykhailo Podolyak said in a TV interview.
Speaking in Florida on Sunday, Donald Trump said of Mr Putin: “I think he wants to stop fighting.
“They [Russia] have a big powerful machine, you understand that. They defeated Hitler and they defeated Napoleon. They’ve been fighting a long time.”
Mr Macron’s meeting is expected to be attended by British Prime Minister Sir Keir, Germany’s Mr Scholz, Danish PM Mette Frederiksen and Poland’s Prime Minister Donald Tusk, alongside other European leaders.
European Commission president Ursula von der Leyen and NATO chief Mark Rutte are also expected at the Paris summit.
The goal of the discussions is to “bring together all partners interested in peace and security in Europe”, a French statement said.
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Meanwhile, representatives from the Trump administration are travelling to Saudi Arabia for peace talks with Russia. The discussions are expected to begin in Riyadh on Tuesday, according to Russian newspaper Kommersant.
Mr Trump’s push for a quick way out of Russia’s war on Ukraine has stirred concern and uncertainty from European leaders.
After a recent phone call with Mr Putin, Mr Trump has – on multiple occasions – said he and the Russian president will meet soon to discuss a peace deal over Ukraine.
He has assured Mr Zelenskyy he will have a seat at the table, but it is unclear if European officials will be invited.
The Ukrainian president has previously said he will not accept any negotiations that do not include his country.