A spokesperson for Ukraine’s president say's they've been trying to talk to Russia’s Vladimir Putin about the build-up of Russian troops on the border, but Putin isn't taking the call.
Kyiv and Moscow have traded blame over the worsening situation in the eastern Donbass region.
President Volodymyr Zelenskiy's office says Russia has rebuffed attempts by Kyiv to start talks over its increased military presence.
While a Kremlin spokesman says they have seen no such request for talks in recent days.
Video show dozens of troop carriers and missile launchers lining up along tracks running through southern Russia, in a region bordering Ukraine.
Moscow denies it is part of the conflict in eastern Ukraine - saying it provides only humanitarian and political support to the separatists.
Zelenskiy spokeswoman says Russia has massed 40,000 troops on their eastern border and more than 40,000 troops in Crimea.
After talks with Turkey at the weekend, Zelenskiy is headed for Paris where he’ll meet French President Emmanuel Macron.
Ukraine fears the Kremlin is engineering a crisis to rally Russians around a foreign enemy ahead of parliamentary elections in September, in an attempt to shift the narrative away from domestic issues such as jailed opposition figure Alexei Navalny.
President Putin on Friday (April 9) accused Ukraine of "dangerous provocative actions" in the Donbass region.
The Kremlin says Russia is free to move forces around its own territory as it sees fit for defensive purposes. The standoff has sparked concern from Ukraine's Western backers.
Washington and the NATO alliance have accused Russia of a "provocative" build-up.