Ukrainian President Volodymyr Zelenskyy made a surprise visit Sunday to the front lines in eastern Ukraine, where Russian forces have turned their focus, attempting to give Ukrainian troops a morale boost.

Zelenskyy "visited the front-line positions of the Ukrainian military" in Lysychansk and Soledar to get a firsthand look at "the operational situation on the front line of defense," a statement from Zelenskyy's office read, according to reports.

"I want to thank you for your great work, for your service, for protecting all of us, our state," Zelenskyy reportedly told his troops. "I am grateful to everyone. I want to wish you and your families good health. Take care of yourselves."

Fighting and heavy artillery strikes remained focused on the Donbas front and especially in Severodonetsk, the largest city of the Lugansk Oblast still not under Russian control.

In Lysychansk, pensioner Oleksandr Lyakhovets said he had just enough time to save his cat before flames engulfed his flat after it was hit by a Russian missile.

"They shoot here endlessly," Lyakhovets, 67, told AFP. "It's a horror show."

After returning to Kyiv on Monday, Zelenskyy said his troops were outnumbered by a "stronger" Russian side, as the two countries' forces battled for control of the eastern city of Severodonetsk.

"We're holding out" in the key city, but "there are more of them and they are stronger," Zelenskyy told journalists in Kyiv, one day after a daring visit to front-line positions in Lysychansk, which sits across the Siverskyi Donets river from Severodonetsk.

Fighting and heavy artillery strikes remained focused on the Donbas front and especially in Severodonetsk, the largest city of the Lugansk Oblast still not under Russian control.

Russian forces pressed their offensive on several other fronts in the east of Ukraine, with Kyiv saying it had repulsed seven attacks around Donetsk and Lugansk.

The Russian defense ministry said its aircraft had hit three arms depots and a fuel storage facility near the village of Kodema, in the Donetsk region.

Both sides have gained and lost ground in recent days in Severodonetsk. Analysts say Ukrainian forces, in holding key areas of the city while attacking other parts of the front lines, have highlighted weaknesses in Russia's capacity to push forward.

"The ability of Ukrainian forces to successfully counterattack in Severodonetsk, the Kremlin's current priority area of operations, further indicates the declining combat power of Russian forces in Ukraine," said the U.S.-based Institute for the Study of War.

Information from AFP was used in this report.

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