Sir Keir Starmer will host a virtual meeting of world leaders today to discuss peacekeeping in Ukraine, and he will use the call to say that now is the time for "concrete commitments", Downing Street has said.
Around 25 leaders are expected to join the call this morning, in which they will discuss in more detail the peacekeeping mission the prime minister has called the 'coalition of the willing'.
Sir Keir will ask allies to continue to ramp up military support to Ukraine.
He will also say countries need to increase economic pressure on Russia in the short term, and be prepared to support an eventual peace deal over the long term, should an agreement be reached.
? Listen to Sky News Daily on your podcast app ?
Attendees will also receive an update on the discussions of defence ministers and military chiefs in Paris this week, and they will all set out details of their own efforts to unlock further military support for Ukraine.
Downing Street has confirmed that some European countries, the EU Commission, NATO, Canada, Ukraine, Australia and New Zealand are expected to join the virtual meeting.
Starmer: The world needs to see action
In a statement ahead of the call, the prime minister said: "We can't allow President Putin to play games with President Trump's deal.
"The Kremlin's complete disregard for President Trump's ceasefire proposal only serves to demonstrate that Putin is not serious about peace.
"If Russia finally comes to the table, then we must be ready to monitor a ceasefire to ensure it is a serious and enduring peace, if they don't, then we need to strain every sinew to ramp up economic pressure on Russia to secure an end to this war."
He went on to accuse the Russian president of "trying to delay" by "saying there must be a painstaking study before a ceasefire can take place".
"The world needs to see action, not a study or empty words and pointless conditions," he continued.
"My message to the Kremlin could not be clearer: stop the barbaric attacks on Ukraine, once and for all, and agree to a ceasefire now. Until then, we will keep working around the clock to deliver peace."
Sir Keir has said Britain could send peacekeepers to Ukraine in the event of a ceasefire deal, but has called on Washington to offer a security 'backstop' to those forces.
Russia casts doubt on potential ceasefire
The meeting comes after Ukraine backed the US's proposal for a 30-day ceasefire.
But the Russian president has said "lots of questions" remain over that proposal, and that a ceasefire must lead to "long-term peace" which "would remove the initial reasons for the crisis".
Read more:
The 'coalition of the willing' that could secure peace in Ukraine
Russia sticks to red lines on 30-day Ukraine ceasefire plan
Trump's fixer was made to wait eight hours to meet Putin
Moscow has reportedly also presented a "list of demands" to the US to end the war, which would include international recognition of Russia's claim to Crimea and four Ukrainian provinces and an agreement that foreign troops not be deployed in Ukraine.
Ukraine's President Volodymyr Zelenskyy said Mr Putin's remarks were "very predictable" and "very manipulative", adding that the Russian president was preparing to reject the ceasefire proposal he agreed with the US.
(c) Sky News 2025: Starmer to host virtual meeting of 'coalition of the willing' - and demand 'c