European leaders have warned against Ukrainian borders being redrawn by force – three days before Russia's Vladimir Putin and US President Donald Trump are due to hold a summit on Ukraine in Alaska.

In a statement, European leaders said "the people of Ukraine must have the freedom to decide their future".

It added the principles of "territorial integrity" must be respected and "international borders must not be changed by force".

The statement was signed by 26 of 27 leaders. Missing from the signatories was Hungary's leader Viktor Orban, who has maintained friendly relations with Russia and has repeatedly tried to block European Union support for Ukraine.

The statement underscored the nervousness felt by Europeans about Moscow's actions in Ukraine, which many countries – particularly those bordering Russia or those in which the memory of Soviet occupation still lingers – believe could pose a direct threat in the near future.

In recent years Sweden and Finland have joined Nato, Baltic countries have reinstated conscription, and Poland has set aside billions to build a barrier alongside its border with Russia.

European countries have a long history of borders being redrawn by bloody wars and are extremely concerned by the prospect of the US allowing that to happen in Ukraine. A legal recognition of Russia's sovereignty over territories it conquered by force is unacceptable to the EU.

Donald Trump has insisted that any peace deal would involve "some swapping of territories" and could see Russia taking the entire Donbas region in eastern Ukraine and keeping Crimea. In exchange it would give up the Kherson and Zaporizhzhia regions, which it partially occupies.

Last week, while admitting that some Ukrainian territory might end up being de facto controlled by Russia, Nato chief Mark Rutte stressed that this should not be formally recognised.

Formal recognition would entail a change to the Ukrainian constitution that needs to be approved by a national referendum, which in turn must be authorised by the Ukrainian parliament. This would be a considerable hurdle for President Volodymyr Zelensky and may lead to the end of his government.

This is why at present "no-one is talking about international formal recognition", analyst Prof Mark Galeotti told the BBC's Today programme.

"We would be recognising that for the moment Russia does control almost 20% of Ukraine but international borders remain what they are," Prof Galeotti said, adding that Zelensky could accept de facto control without changing the constitution.

In their statement, European leaders said "Russia's war of aggression against Ukraine has wider implications for European and international security", and stressed the need for a "just and lasting peace".

They also said Ukraine should be capable of "defending itself effectively" and pledged to continue providing military support to Kyiv, which was "exercising its inherent right of self defence".

"The European Union underlines the inherent right of Ukraine to choose its own destiny and will continue supporting Ukraine on its path towards EU membership," the statement concluded.

Denting the apparent unity of the declaration was a line in smaller print at the bottom of the page pointing out that "Hungary does not associate itself with this statement".

In a post on social media its leader Viktor Orban said he had opted out of supporting the statement as it attempted to set conditions for a meeting to which the EU was not invited and warned leaders not to start "providing instructions from the bench".

He also urged the EU to set up its own summit with Russia – though EU leaders have been shunning direct talks with Moscow since it launched its invasion of Ukraine in February 2022.

On Monday Trump revealed he had sought Orban's advice over the chances of Ukraine winning against Russia on the battlefield. "He looked at me like, 'What a stupid question'," Trump said, suggesting that Orban felt Russia would continue to wage war until it beat its adversary.

Trump and his Russian counterpart Vladimir Putin are expected to meet in Alaska on Friday.

Before that, EU leaders are due to hold talks with Trump on Wednesday. UK Prime Minister Sir Keir Starmer will also join the call and said on Monday that peace would have to be "built with Ukraine, not imposed upon it".

They will be hoping to put the security of the European continent and Ukrainian interests at the forefront of his mind – at a time when nervousness is growing that the peace imposed on Ukraine may end up being neither "just" nor "lasting".