Liz Truss has warned leaders including Emmanuel Macron that the West cannot “sell out Ukraine” for a “quick end” to the war, calling on G7 and Nato countries to commit more arms and funding to the country.
In a joint article for The Telegraph with Dmytro Kuleba, her Ukrainian counterpart, the Foreign Secretary said Vladimir Putin, the Russian president, will “only be serious about negotiations once the Ukrainian people have pushed his troops back”.
The pair added: “The Ukrainian people do not have the luxury to feel fatigued. Nor can the rest of the free world.”
Mr Macron, who has talked of spending 100 hours on the phone to Putin since December, has been accused of wanting Ukraine to make concessions to secure a peace agreement – although the Elysee Palace insists any deal must respect Ukraine’s sovereignty.
Ms Truss and Mr Kuleba wrote: “To get peace and protect our way of life, Ukraine and the free world need to stay strong and united. We must ignore the defeatist voices who insist people are beginning to tire and who propose to sell out Ukraine for a quick end to the unrelenting horror.”
Boris Johnson is expected to echo the call when he attends the opening of the G7 conference in Munich on Sunday. Volodymyr Zelensky, the Ukrainian president, will address Western leaders and call for more economic and military support from Western powers.
Following the address, Mr Johnson will implore his counterparts to commit to long-term support and warn leaders away from thinking about de-escalation of the conflict.
Ms Truss and Mr Kuleba hinted that the UK and US should be closely involved in any peace negotiations when they begin.
The Foreign Secretary is thought to be concerned that the 2014 agreement to end the war in the Donbas region of Ukraine, which was mediated by France and Germany, conferred special status on the separatist areas of Donetsk and Luhansk and ceded territory to Putin.
“There can be no negotiated settlement which replicates the Minsk Agreement, which came at the expense of Ukraine’s sovereignty, security and territorial integrity,” they said.
“Those who propose sacrificing Ukraine’s land are actually proposing paying in Ukrainian blood for the illusion of peace. It will be a mirage unless accompanied by the restitution of Ukrainian territory and the containment of Putin’s imperialism.”
Ms Truss and Mr Kuleba said it was “imperative that the G7 and Nato this week demonstrate that their commitment to Ukraine will never be surpassed by Putin’s determination to seize it”.
“That means increasing and speeding up their supply of heavy weapons, continuing to sanction all those colluding in Putin’s war, and cutting off imports of Russian energy completely,” they added.
Although other world leaders have also visited Mr Zelensky in Kyiv, Mr Johnson has sought to portray Britain as Ukraine’s closest ally.
“The UK, US and other European leaders all want to see the same thing – a democratic, sovereign and thriving Ukraine that is able to defend itself against further aggression,” the Prime Minister's official spokesman said on Saturday.
“The PM visited Kyiv last week for discussions with President Zelensky, who made clear that Ukraine has no interest in surrendering sovereignty.”
The UK is also pledging to guarantee another £429 million in World Bank loans to Ukraine, amid concerns its government could collapse by the autumn without further support.
The pledge brings Britain’s total commitment to £1.5bn, including £1.3bn in loan guarantees and £220m in direct humanitarian aid.
This week will see world leaders converge first on Munich for the G7 summit, then on Madrid for a full conference of Nato members.
Representatives for Finland and Sweden are also expected to join a meeting to discuss their accession to Nato.
Leaders will discuss the war in Ukraine’s impact on the global economy, food security and the future of Western alliances.
Ahead of the summits, Mr Johnson said: “Future generations will be awed and inspired by the truly heroic Ukrainian resistance in the face of Putin’s barbarism.
“Ukraine can win and it will win. But they need our backing to do so. Now is not the time to give up on Ukraine.
“The UK will continue to back Ukraine every step of the way, because we know that their security is our security, and their freedom is our freedom.”