Sir Keir Starmer is meeting with allies of Ukraine at the Johannesburg G20 summit on Saturday to seek to “strengthen” a plan secretly drafted by the US to end the war with Russia.
Washington reportedly pressed Kyiv to accept the agreement which would see the invaded country make major concessions including giving up territory and cutting the size of its army.
Western nations are scrambling to respond to the proposals on the sidelines of the South African meeting shunned by Donald Trump.
The Prime Minister held 25-minute talks with France’s Emmanuel Macron and Germany’s Friedrich Merz, before the meeting was expanded to include a dozen G7 and G20 leaders including from Japan, Canada, Italy, Norway and the European Union.
The 28-point plan is said to have been negotiated by the US president’s special envoy Steve Witkoff and Kremlin representative Kirill Dmitriev, with Kyiv and European allies left out of the process.
Before Saturday’s summit, where media access is limited, Sir Keir said: “Ukraine’s friends and partners will meet in the margins of the G20 summit to discuss how we can secure a full ceasefire and create the space for meaningful peace negotiations.
“We will discuss the current proposal on the table, and in support of President Trump’s push for peace, look at how we can strengthen this plan for the next phase of negotiations.”
He continued there “is only one country around the G20 table that is not calling for a ceasefire” as he condemned Moscow for sending nearly 1,000 drones and 54 precision guided missiles in the past week alone.
The Prime Minister said: “Ukraine has been ready to negotiate for months, while Russia has stalled and continued its murderous rampage.
“That is why we must all work together, with both the US and Ukraine, to secure a just and lasting peace once and for all.
“We will continue to co-ordinate closely with Washington and Kyiv to achieve that.”
Russian President Vladimir Putin, who like Mr Trump is not attending the gathering of the world’s leading economies, on Friday cautiously welcomed the US proposal, saying it “could form the basis of a final peace settlement”.
But he said the plan had not been discussed with the Russian side “in any substantive way” and that he assumed this was because the US had not been able to get Ukraine’s consent.
Earlier on Friday, Ukrainian President Volodymyr Zelensky said in a video address to his nation that it faced “one of the most difficult moments” in its history, facing a choice between “losing its dignity or the risk of losing a key partner”.
It followed his 40-minute call with Sir Keir, Mr Macron and Mr Merz, in which the European leaders emphasised that Ukraine “must determine its future under its sovereignty”.
The Prime Minister said they had emphasised to Mr Zelensky their support for Ukraine and the “fundamental principle” that Kyiv should be in charge of its own destiny.
Mr Trump told Fox News Radio on Friday he wanted a response to the peace plan from Ukraine by Thursday, while suggesting an extension could be possible.
The US president is boycotting the November 22-23 leaders’ summit over widely rejected claims that white people are being persecuted in South Africa.
Asked what it meant to “strengthen” Washington’s plans, Downing Street declined to “get ahead of those discussions” but denied they were viewed as weak by friends of Kyiv.
Pressed on whether Britain had been cut out of Mr Trump’s peace negotiations, Sir Keir’s spokesman said he did not “accept that at all” as he stressed the “excellent relationship” between the US and UK leaders.
The Prime Minister’s language has been cautiously diplomatic and has praised US efforts to end the four-year conflict.
No 10 has defended the Labour leader’s attendance at the G20 summit – coming days before the Budget is expected to raise taxes and despite the US president’s absence – saying he would use it to shore up support for Kyiv and strike business deals.
He will announce a £4 billion maritime agreement in a call with Indonesian President Prabowo Subianto on Saturday.
Led by British defence firm Babcock, the programme will see the two countries jointly develop capability for Indonesia’s navy, creating 1,000 jobs in Rosyth, Bristol and Plymouth.
