Russia has stepped up attempts to break through Ukraine's defenses with heavy fighting in the north and east of the country, underlining Kyiv's need for more Western weapons, Ukrainian officials was quoted as saying by Reuters on Friday.
The Ukrainian military said fierce battles were under way. A day after Ukraine said Moscow fired more than 50 missiles aimed at energy facilities and killed at least 11 people, hours after Germany and the U.S. announced their plans to provide modern tanks to the country.
Russia does not respond to the latest claim.
After weeks of wrangling, Germany and the United States have promised Ukraine dozens of modern tanks to help the latter in the Russia-Ukraine conflict, opening the way for Canada, Poland, Finland, Norway and others to follow suit.
Ukraine hailed Germany and U.S.' move as a potential turning point in its fight in the Russia-Ukraine conflict, while Russia see by it as "direct involvement" in the conflict from the West.
Russia chided U.S. President Joe Biden, saying he held the key to ending the conflict in Ukraine, which Moscow says does Washington's bidding, but had not used it.
Local officials on Friday reported heavy shelling in the north, northeast and east of Ukraine, scene of some of the heaviest combat since the conflict began on February 24 last year.
Protests and worries as West pledges tanks to Kyiv
The latest promise by Western countries to send high-tech battle tanks to Ukraine has aroused not only protests and condemnation, but also worries that more advanced weaponry could be next.
On Thursday night, a protest against supplies of German tanks and weapons was held in the German city Munich.
Hundreds of people carrying flags and banners with calls for peace and criticism of weapons supplies to Kyiv gathered in the city's central Marienplatz square.
Germany's decision to give tanks to Ukraine also drew condemnation from Mexican President Andres Manuel Lopez Obrador, who said at a press conference on Wednesday that the German government succumbed to media pressure.
Noting Germany did not want to get too involved in the conflict between Russia and Ukraine, Obrador said that "contrary to the opinion of the German population, the majority of Germans, the government decides to send more weapons to Ukraine due to pressure from the German media."
Reports and analysis also expressed worries about what the West's tank promise could lead to. Given tanks for Ukraine once seemed unthinkable, an analysis on CNN considered whether fighter jets could be next.
And an opinion piece in the Guardian by Martin Kettle argued that sending tanks to Ukraine makes clear this is now a Western war against Russia, and that Ukraine has inescapably placed more of its future in U.S. hands.
(With input from agencies)