European leaders on Sunday said only "an approach that combines active diplomacy, support to Ukraine and pressure" on Russia can bring the war in Ukraine to an end.

On Saturday, US Vice President JD Vance met British Foreign Secretary David Lammy, and representatives of Ukraine and European allies on Saturday at Chevening House, a country mansion southeast of London, to discuss Trump's push for peace.

A joint statement from the French, Italian, German, Polish, British and Finnish leaders and the president of the European Commission welcomed Trump's efforts, while stressing the need to maintain support for Ukraine and pressure on Russia.

Earlier, Ukraine's President Volodymyr Zelensky warned that Kyiv won't surrender land to Russia to buy peace, after Washington and Moscow agreed to hold a summit in a bid to end the war.

Presidents Vladimir Putin and Donald Trump will meet in the US state of Alaska on August 15, to try to resolve the three-year conflict, despite warnings from Ukraine and Europe that Kyiv must be part of negotiations.

Announcing the summit on Friday, Trump said that "there'll be some swapping of territories to the betterment of both" sides, without providing further details.

"Ukrainians will not give their land to the occupier," Zelensky said on social media hours later.

"Any decisions against us, any decisions without Ukraine, are also decisions against peace. They will achieve nothing," he said.

Zelensky also urged Ukraine's allies to take "clear steps" towards achieving a sustainable peace, during a call with Britain's Prime Minister Keir Starmer.

National security advisors from Kyiv's allies -- including the United States, EU nations and the UK -- gathered in Britain on Saturday to align their views ahead of the Putin-Trump summit.

French President Emmanuel Macron, following phone calls with Zelensky, Starmer and German Chancellor Friedrich Merz, said "the future of Ukraine cannot be decided without Ukrainians" and that Europe also had to be involved in the negotiations.

Three rounds of talks between Russia and Ukraine this year have failed to bear fruit, and it remains unclear whether a summit could bring peace any closer as the sides' positions are still far apart. (Agencies)