Ukraine acknowledged on Friday it was taking heavy losses in Russia's assault in the east, but Moscow's forces have lost many more soldiers.

Oleksiy Arestovych said Ukraine had lost control of some towns and villages - but claimed Russia's own casualties had been "colossal".

U.N. Secretary-General Antonio Guterres said Ukraine has become “an epicenter of unbearable heartache and pain”, a description highlighted a short time later by the first Russian strike on the capital since Moscow’s forces retreated weeks ago.

Guterres said after meeting Zelenskiy in Kyiv on Thursday that intense discussions were under way to enable the evacuation of the Azovstal steel plant, which has been pounded by Russian forces occupying Mariupol.

Ukraine hopes on Friday to evacuate civilians who are holed up in a vast steel works with the last fighters defending the southern city of Mariupol.

"An operation is planned today to get civilians out of the plant," President Volodymyr Zelenskiy's office said without giving details.

Explosions were reported across the country, in Polonne in the west, Chernihiv near the border with Belarus, and Fastiv, a large railway hub southwest of the capital. The mayor of Odesa, in southern Ukraine, said rockets were intercepted by air defenses.

Moscow regards winning the "Battle for Donbas" as crucial if it is to achieve its stated objective of securing control over the Donetsk and Luhansk regions in the east, Britain's defence ministry said. "Fighting has been particularly heavy around Lysychansk and Severodonetsk, with an attempted advance south from Izium towards Sloviansk," it said on Twitter.

Russian forces are continuing to make advances in east of the country but strong resistance from Ukrainian troops is slowing their progress.
-AP/Reuters/BBC