The Kremlin said on Monday that the idea of holding peace talks without Russia was ridiculous, after Ukrainian President Volodymyr Zelensky said he hoped to hold a spring summit in Switzerland to discuss his peace vision with Kyiv's allies.

"We have repeatedly said that this is a strange format, to say the least, because certain peace plans are being implemented without the participation of Russia, which in itself is frivolous and even laughable," Kremlin spokesman Dmitry Peskov told reporters.

The remarks were made after Zelensky's chief of staff Andriy Yermak said on Sunday that a blueprint from the summit in Switzerland could be handed to Russia at a later date.

Moscow has repeatedly said it is open to talks, but that these must recognize the "new realities on the ground". Ukraine demands the restoration of its territorial integrity and a full withdrawal of Russian forces.

At a gathering of nearly 20 European leaders in Paris on Monday, French President Emmanuel Macron said the consensus among European leaders was that more efforts are needed to help Ukraine financially and militarily.

"There is no consensus at this stage … to send troops on the ground," Macron told reporters. "Nothing should be excluded. We will do everything that we must so that Russia does not win."

Macron invited his European counterparts to the Elysee Palace for a hastily arranged meeting to discuss how to ramp up ammunition supplies to Ukraine amid what his advisers say is an escalation in the Russian offensive over the past few weeks.

"We all agree we don't want to go to war with the Russian people, but we're determined to keep escalation under control," said Macron, adding that the meeting was meant to see how to "do more in terms of military support and budget support".

Addressing the leaders via video link, Zelensky backed Macron's warning about an escalation of the conflict. He warned earlier on Sunday that Russia was preparing for a new offensive starting in late May or summer, but Kyiv has a clear battlefield plan of its own.

As the conflict now enters its third year, Ukraine has suffered setbacks on eastern battlefields, with its generals complaining of shortages of arms and soldiers.

Slovak Prime Minister Robert Fico said on Monday that several NATO and European Union members are considering sending soldiers to Ukraine on a bilateral basis.

Fico offered no details and other European leaders did not immediately comment on his remarks.

He said this ahead of a meeting of European leaders in Paris on Monday. "I will limit myself to say that these (in preparation for the Paris meeting) imply a number of NATO and EU member states are considering that they will send their troops to Ukraine on a bilateral basis," Fico said after a meeting of Slovakia's security council.

NATO made no immediate comments on Fico's remarks, and Czech Prime Minister Petr Fiala said his country "certainly is not preparing to send any soldiers to Ukraine".