Ukrainian forces have advanced around Bakhmut, Deputy Defence Minister Hanna Maliar has said, describing the eastern city as the “epicentre of hostilities”.
She did not say whether a long awaited counter-offensive had begun.
Separately, Russia’s military said it had repelled a new attack in the eastern Donetsk region on Monday.
Bakhmut has for months been at the heart of fierce fighting. It has little strategic value – but is important symbolically both for Kyiv and Moscow.
Monday’s claims by Ukraine and Russia have not been independently verified.
help the enemy.
“Plans love silence. There will be no announcement of the start,” the defence ministry said in a recently posted video. It featured masked and well-armed troops holding their fingers against their lips.
It will take Ukraine time to achieve its goal of liberating territory taken by Russia as far back as nine years ago.
And Moscow has had time to prepare. It means if Ukraine is able to mount a counter-offensive, it is going to take.
Much is at stake because the government in Kyiv needs to show the people of Ukraine – and Western allies – that it can break through Russian lines, end the effective military deadlock and recapture some of its sovereign territory.
Elsewhere, fighters opposed to the government in Moscow say they have captured some Russian soldiers in Belgorod, near the border with Ukraine.
The claim was made by the Liberty of Russia Legion (FRL), which described the announcement as a joint statement with the Russian Volunteer Corps (RDK).
Both groups want to topple Russian President Vladimir Putin and oppose the full-scale invasion of Ukraine that he launched in February last year.
Russia has blamed Ukraine for recent attacks in its border territories, but Kyiv denies being directly involved.
Meanwhile, President Zelensky met UK Foreign Secretary James Cleverly in Kyiv on Monday.
Mr Zelensky said the pair discussed expectations from the upcoming Nato summit in Vilnius in July and Ukraine’s peace proposals.