Ukraine invasion: Kyiv says Russia using 'all its power' to capture eastern city

Ukraine said on Saturday its forces were managing to push back against Russian troops in fierce fighting in Severodonetsk despite Russia "throwing all its power" into capturing the strategic eastern city.

At least seven civilians were reported killed in the Lugansk region where Severodonetsk is located and in the southern city of Mykolaiv, while a revered wooden church was reported to be on fire because of the fighting.

Lugansk regional governor Sergiy Gaiday said in an interview posted online that the invading forces had captured most of Severodonetsk, but that Ukraine's forces were pushing them back.

"The Russian army, as we understand, is throwing all its power, all its reserves in this direction," said Gaiday.

"Our soldiers have managed to redeploy, build a line of defence," said the city's mayor, Oleksandr Striuk, in a televised interview broadcast on Telegram Saturday.

"We are currently doing everything necessary to re-establish total control" of the city, he added. But he acknowledged the situation was "quite difficult", with street fighting and artillery exchanges.

Russia's army claimed some Ukrainian military units were withdrawing from the city.

Severodonetsk is the largest city still in Ukrainian hands in the Lugansk region, where Russian forces have been gradually advancing in recent weeks after retreating or being repelled from other areas, including around the capital Kyiv.

Tens of thousands of people have been killed, millions forced to flee and towns turned into rubble since Russian President Vladimir Putin ordered an all-out assault on his pro-Western neighbour on February 24.

Western powers have slapped increasingly stringent sanctions on Russia and supplied arms to Ukraine but divisions have emerged on how to react.

French President Emmanuel Macron said on Friday Putin had committed a "fundamental error" but said Russia should not be "humiliated" so that a diplomatic solution could be found.

Ukrainian Foreign Minister Dmytro Kuleba reacted on Saturday by saying such calls "only humiliate France" and any country taking a similar position.

"It is Russia that humiliates itself. We all better focus on how to put Russia in its place. This will bring peace and save lives," he said.

Despite diplomatic efforts, the conflict has raged in the south and east of the country.

Ukrainian officials announced on Saturday the death of four foreign military volunteers fighting Russian forces but did not specify when or under what circumstances they died.

The International Legion of Defence of Ukraine, an official volunteer brigade, named the men and published photos of them, saying they were from Germany, the Netherlands, Australia and France.

The deaths of the two men named from the Netherlands and Australia had already been reported and France's foreign ministry said on Friday a French volunteer fighter had been killed in combat.

Ukraine also reported two victims from a Russian missile strike on Odessa in the southwest, without specifying if they were dead or injured.

Russia's defence ministry said it had struck a "deployment point for foreign mercenaries" in the village of Dachne in the Odessa region.

It also claimed a missile strike in the northeastern Sumy region on an artillery training centre with "foreign instructors".