President Volodymyr Zelensky has said Ukraine would reject any Russian proposal to give up the Donbas region in exchange for a ceasefire, warning it could be used as a springboard for future attacks.

Zelensky was speaking ahead of a meeting between US President Donald Trump and Russian counterpart Vladimir Putin in Alaska on Friday.

Trump has said any peace deal would involve “some swapping of territories” and it is believed one of Putin’s demands is that Kyiv surrenders the parts of the Donbas it still controls.

Meanwhile Russia’s troops have continued their summer offensive, making a sudden thrust near the eastern town of Dobropillia and advancing 10km (six miles) in a short period of time.

Zelensky admitted the advance had taken place in “several spots” but said Kyiv would soon destroy the units involved in the attack.

While downplaying Russia’s advance, he added it was “clear to us” that Moscow’s objective was to create a “certain information space” before Putin meets Trump that “Russia is moving forward, advancing, while Ukraine is losing”.

No official details have emerged on what demands Vladimir Putin could make when he meets Donald Trump in Anchorage on Friday.

The Donbas – made up of the eastern regions of Luhansk and Donetsk – has been partly occupied by Russia since 2014.

Moscow now holds almost all of Luhansk and about 70% of Donetsk but speaking to reporters on Tuesday, Zelensky reaffirmed that Ukraine would reject any proposal to leave the Donbas.

“If we withdraw from the Donbas today – our fortifications, our terrain, the heights we control – we will clearly open a bridgehead for the Russians to prepare an offensive,” he said.

Zelensky has previously insisted that Ukrainians would not “gift their land to the occupier”, and pointed to the country’s constitution, which requires a referendum before a change in its territory.

In his nightly address on Tuesday, Zelensky also said Moscow was preparing new offensives on three parts of the front – Zaporizhzhia, Pokrovsk and Novopavlov areas.

Last week Trump said there would be “some swapping of territories to the betterment of both” Russia and Ukraine – sparking concern in Kyiv and across Europe that Moscow could be allowed to redraw Ukraine’s borders by force.

Russia currently controls just under 20% of Ukrainian territory.

The White House on Tuesday said the Alaska talks would be a “listening exercise” for Trump and added having him and Putin sit down in the same room would give the US president “the best indication on how to end this war”.

It follows Trump describing the summit as a “feel-out meeting” on Monday, seeming to tone down expectations that Friday’s meeting could bring Ukraine and Russia closer to peace.

When he announced the summit last week, Trump sounded positive that the meeting could result in concrete steps towards peace.

“I think my gut instinct really tells me that we have a shot at it,” he said.

But Ukrainian President Zelensky once again expressed serious doubts that the talks could result in a positive outcome for Kyiv, which has been excluded from the summit. “I don’t know what they will talk about without us,” he said.

Zelensky has steered clear of criticising Trump but in recent days his frustration at being sidelined has become apparent, and on Tuesday he said the choice of Alaska as a location was a “personal victory” for Putin.

“He is coming out of isolation, because they are meeting with him on US territory,” he said.

The Ukrainian leader has previously said any agreements without Kyiv’s involvement would amount to “dead decisions”.

On Wednesday, Zelensky is due to join a virtual meeting with Donald Trump, EU leaders, UK Prime Minister Sir Keir Starmer and Nato chief Mark Rutte.

All sides will try to convince Trump of the need not to be swayed by Putin when the two meet at the hastily-organised summit.