US President Donald Trump on Wednesday warned of "very severe consequences" if Russian President Vladimir Putin doesn't agree to stop the Ukraine war after Friday's summit, media reports said.

US President Donald Trump on Wednesday warned of "very severe consequences" if Russian President Vladimir Putin doesn't agree to stop the Ukraine war after Friday's summit, media reports said.

Trump was "very clear" during a virtual meeting on Wednesday with European leaders that the US wants to achieve a ceasefire at the upcoming US-Russia summit in Alaska, French President Emmanuel Macron said.

In the same meeting, Ukrainian President Volodymyr Zelenskyy told the group that Putin "is bluffing" ahead of the planned meeting with Trump.

Zelenskyy said, Putin "is trying to apply pressure ... on all sectors of the Ukrainian front" in an attempt to show that Russia is "capable of occupying all of Ukraine."

Putin is also bluffing about sanctions, "as if they do not matter to him and are ineffective. In reality, sanctions are very helpful and are hitting Russia's war economy hard," the Ukrainian President said.

Following the video conference between Trump, Zelenskyy, and other European leaders, Macron told the media that Trump prioritised a ceasefire between Ukraine and Russia.

He added that Trump had been clear that "territorial issues relating to Ukraine ... will only be negotiated by the Ukrainian president."

Following his meeting Friday with the Russian leader, Trump will also "seek a future trilateral meeting" - one involving Trump, Putin, and Zelenskyy, Macron said.

"I think that's a very important point in this regard. And we hope that it can be held in Europe, in a neutral country that is acceptable to all parties," Macron said.