EU foreign-policy chief Josep Borrell has assured the Ukrainian government of "unwavering EU support" in the conflict with Russian-backed separatists in the east of the country.
Borrell said on Twitter on April 4 that he spoke by phone with Ukrainian Foreign Minister Dmytro Kuleba and added that he was "following with severe concern the Russian military activity surrounding Ukraine."
He said the matter would be further discussed at the next meeting of EU foreign ministers.
Borrell's call with Kuleba comes after a call on April 2 between U.S. President Joe Biden and Ukrainian President Volodymyr Zelenskiy in which Biden sought to reassure Zelenskiy of "unwavering" U.S. support for Ukraine's sovereignty and territorial integrity.
Ukrainian and Russian-backed separatists in the Donetsk region have accused each other of attacks over the weekend.
The tensions come after Ukraine alleged last week that Russia had been massing troops at their shared border.
Kremlin spokesman Dmitry Peskov responded by saying that Russia was "moving troops within its own territory at its own discretion, and this shouldn't concern anyone."
Russia, which annexed Ukraine's Crimea region in 2014, has consistently denied involvement in the fighting in eastern Ukraine's Luhansk and Donetsk regions despite significant evidence to the contrary.
"Russia is not interested in any conflict with Ukraine, especially a military one," Deputy Foreign Minister Andrei Rudenko told state news agency RIA Novosti in response to the recent allegations.
Germany, Russia, France, and Ukraine are part of the so-called Normandy Format set up to try to resolve the Ukraine conflict.
Germany and France recently expressed concern about the "growing number of cease-fire violations."
"We are closely monitoring the situation and in particular Russian troop movements and call on all sides to show restraint and to work towards immediate de-escalation," they said in a statement.