French President Emmanuel Macron and German Chancellor Angela Merkel will hold talks on Friday with Ukrainian President Volodymyr Zelensky in a show of support for the former Soviet state, which fears a Russian invasion.
A massive build-up of Russian troops along the border has sparked new tensions in eastern Ukraine, where government forces have been battling pro-Russian separatists since 2014.
President Macron will receive Zelensky for lunch in Paris and both men will then talk with Chancellor Angela Merkel by video link, the French presidency said on Thursday.
"Ukraine's sovereignty is under threat," a statement from Macron's office said, adding: "All our work is aimed at avoiding an escalation and defusing tensions."
Zelensky's meeting with the leaders of France and Germany, who have been mediators in the conflict since 2015, comes as Ukraine accuses Russia of threatening to destroy it.
Threat of war and destruction
"They are openly threatening Ukraine with war and the destruction of Ukrainian statehood," Foreign Minister Dmytro Kuleba told a press conference co-hosted with his counterparts from Estonia, Latvia and Lithuania.
"The red line of Ukraine is the state border. If Russia crosses the red line, then it will have to suffer," he warned.
In recent weeks Moscow has amassed tens of thousands of troops along Ukraine's northern and eastern borders, as well as on the Crimean peninsula which Moscow annexed in 2014.
Russia's defence ministry says the troops are merely responding to "threatening" actions by the Nato alliance and participating in military drills.
Ukraine, where a pro-Kremlin president was ousted in a popular uprising in 2014, has made clear its ambition to join Nato.
On Wednesday, US President Joe Biden and Germany's Merkel called on Russia to reduce its border deployment.
Biden has proposed a summit with Putin -- an offer that Russia is still considering.
Some observers have cast the escalation as an attempt by both Moscow and Kiev to test new US President Biden to see how far he is willing to go to defend Washington's ally and confront Russia.