British Prime Minister Andy Burnham, in Kyiv on his first foreign visit since taking office in July, urged the gathering of the "Coalition of the Willing" to "do everything we can" to bolster Ukraine's defences against Russian air strikes.
President Volodymyr Zelenskiy had earlier praised the resilience of the Ukrainian people during more than four years of war.
"Ukraine absolutely wants peace, but it is not ready to simply surrender," Zelenskiy said on Monday, adding Russia would not halt its aggression even if Ukraine ceded to its demands for more territory in the country's east.
Wearing a traditional Ukrainian embroidered shirt, Zelenskiy thanked foreign leaders for travelling to Kyiv to show their support on the 35th anniversary of Ukraine's break from the Soviet Union.
Standing alongside Zelenskiy and European Council President Antonio Costa, Burnham said his choice of Kyiv for his first foreign visit showed the importance he attached to assisting in Ukraine's defence.
"We are with you in this struggle all the way, heart and soul," Burnham said, vowing to continue that support "despite Russia's outrageous threats to my country."
"This is the moment to keep up the pressure on Russia. The moment to squeeze their ability to fund this illegal war," Burnham said, calling for further economic sanctions.
Britain on Monday announced it would allow Kyiv access to classified technology to start its own production of Storm Shadow long-range cruise missiles, capable of carrying out strikes deep within Russia. France has already given its assent to licence the technology for the European missile.
In response, the Kremlin said the use of classified British technology would "add fuel to the fire" of their worsening relations, after it warned London last week there would be "consequences" for supplying drones to Kyiv.
With Russia escalating its ballistic missile attacks on Ukrainian cities, Kyiv is suffering an acute shortage of the US-made Patriot air defence interceptors — the only weapon in its arsenal capable of downing such missiles.
French President Emmanuel Macron, co-chairing the coalition meeting via video link, said a string of deadly attacks on Ukrainian cities in recent weeks had shown that allies needed to step up the deliveries of interceptors and France would do its part.
"I think it's very important that all of us accelerate in terms of delivery," Macron told the meeting, urging countries not to back down in the face of Russian intimidation.
"The bottom line is, for me, very clear: keep calm and carry on."
Hundreds of thousands of people have been killed, and swathes of Ukrainian territory have been laid waste, since Russia launched its full-scale invasion on February 24, 2022.
US-led peace talks to bring a lasting end to the war fell apart earlier in 2026 as Ukraine refused Russian demands to cede more territory. Fighting continues along a 1200-km front line and Ukraine has succeeded in bringing Russian advances overall to a virtual halt this year.
Ukraine has increased its long-range attacks on Russian refineries and logistics infrastructure, aimed at undermining Moscow's war effort.
It hit four logistics hubs owned by Russia's second-largest online retailer Ozon in southern Russia in drone strikes on Monday, the company said.
In a sombre moment, the Ukrainian leader rewarded fallen soldiers with state awards, which he presented to their mothers and family members.
He also announced the return of 10 Ukrainian servicemen, who were previously listed as missing in action, as part of a special prisoner exchange with Russia.
"We remember each and every one who remains in captivity," Zelenskiy said, promising to do everything possible to bring them home.
with PA
