The Kremlin has issued an ultimatum to Joe Biden after the US president said he was willing to meet Russian dictator Vladimir Putin in an attempt to end the war in Ukraine.

Biden claimed he would only meet Putin if Russia was genuinely serious about bringing peace to eastern Europe.

But Kremlin spokesman Dmitry Peskov quickly hit back and said Moscow would only be willing to discuss an end to the conflict if the West recognised Russia’s claims over four annexed Ukrainian territories.

In September, Moscow held so-called referendums in four regions of Ukraine - Donetsk, Kherson, Lugansk and Zaporizhzhia - and said residents had voted in favour of becoming subjects of Russia.

The United Nations has condemned the “attempted illegal annexation” of Ukrainian land.

“What did President Biden say in fact? He said that negotiations are possible only after Putin leaves Ukraine,” Kremlin spokesman Peskov told reporters, adding Moscow was “certainly” not ready to accept those conditions.

“The special military operation is continuing,” Peskov said, using the Kremlin term for the assault on Ukraine.

Russian President Vladimir Putin puts on protective glasses as he visits a military training center for mobilised reservists in Ryazan Region, Russia. Photo / AP

Biden had earlier spoken during a state visit by French President Emmanuel Macron, who said he will speak again to Putin after his trip to Washington and has warned against cutting off the Russian leader.

At a joint news conference with Macron, Biden said he had no immediate plans to contact Putin but left open the possibility.

US President Joe Biden, right, and Emmanuel Macron, France's president, toast during a state dinner on the South Lawn of the White House in Washington, DC. Photo / Getty Images

“I’m prepared to speak with Mr Putin if in fact there is an interest in him deciding he’s looking for a way to end the war. He hasn’t done that yet,” Biden said.

“If that’s the case, in consultation with my French and my Nato friends, I’ll be happy to sit down with Putin to see what he has in mind. He hasn’t done that yet.”

Closing ranks, Biden and Macron both vowed long-term support to Ukraine as it fights off Russian invaders.

“There’s one way for this war to end - the rational way. Putin to pull out of Ukraine, number one. But it appears he’s not,” Biden said.

“Bombing nurseries, hospitals, children’s homes. It’s sick what he’s doing.

“The idea that Putin is ever going to defeat Ukraine is beyond comprehension,” he added.

“He’s miscalculated every single thing he initially calculated.”

As Russia amassed troops along the Ukrainian border before the February 24 invasion, Biden and his top diplomat, Secretary of State Antony Blinken, both spoke to Russia and warned of consequences if it attacked.

Destroyed buildings following Russian shelling in Bakhmut, Donetsk region, Ukraine. Photo / AP

Blinken is known to have spoken to his Russian counterpart, Foreign Minister Sergei Lavrov, once since the invasion but narrowly on a proposal to free jailed Americans.

Macron said he planned to talk to Putin in part over the security of the Russian-occupied Zaporizhzhia plant in Ukraine.

“I will continue to talk to President Putin,” Macron said, calling for efforts “to prevent escalation and to achieve concrete results”.

But like Biden, Macron said he would not push Ukrainian President Volodymyr Zelenskyy into any peace plan that he does not accept.

“We will never urge the Ukrainians to make a compromise that will not be acceptable for them,” Macron said.

Macron said Zelenskyy has shown a “real willingness” to pursue peace, adding, “Our job must be to work together with him.”

Zelenskyy since the invasion has insisted on Ukraine retaking all territory seized by Russia.