Speaking at a news conference in Moscow on Thursday, Putin said of the ceasefire proposal: "The idea is right - and we support it - but there are questions that we need to discuss."

A ceasefire should lead to "an enduring peace and remove the root causes of this crisis", Putin said.

"We need to negotiate with our American colleagues and partners," he said. "Maybe I'll have a call with Donald Trump."

Putin added: "It will be good for the Ukrainian side to achieve a 30-day ceasefire.

"We are in favour of it, but there are nuances."

One of the areas of contention is Russia's Kursk region, Putin said, where Ukraine launched a military incursion last year and captured some territory.

He claimed Russia was fully back in control of Kursk, and said Ukrainian troops there "have been isolated".

"They are trying to leave, but we are in control. Their equipment has been abandoned."

"There are two options for Ukrainians in Kursk - surrender or die."

Outlining some of his questions over how a ceasefire would work, Putin asked: "How will those 30 days be used? For Ukraine to mobilise? Rearm? Train people? Or none of that? Then a question – how will that be controlled?"

"Who will give the order to end the fighting? At what cost? Who decides who has broken any possible ceasefire, over 2,000km? All those questions need meticulous work from both sides. Who polices it?"

• Is Putin ready for a ceasefire or playing for time?