On 100th day of Russian attack, Zelensky claims 'victory will be ours'

Ukraine will emerge victor in the war started by Russia, President Volodymyr Zelensky said Friday as Moscow's attack on its neighbour entered its 100th day with Russian troops pounding the Donbas region.

Thousands of people have been killed, millions sent fleeing and towns turned into rubble, since Russian President Vladimir Putin ordered his troops into Ukraine on February 24.

Russia's advance has been slowed by a fierce Ukrainian resistance which repelled them from around the capital and forced Moscow to shift its aims towards capturing the east.

Russia has since taken a fifth of Ukrainian territory -- tripling the land under its occupation from 2014 when it seized Crimea and parts of Donbas.

Moscow assessed that "certain results have been achieved," Kremlin spokesman Dmitry Peskov told reporters, pointing to the "liberation" of some areas from what he called the "pro-Nazi armed forces of Ukraine".

But Zelensky said Russia will not prevail appearing in a video accompanied by the same key political leaders also shown in a video posted on February 24 when they vowed to defend their country.

"Our team is much bigger. The Armed Forces of Ukraine are here. The most important -- the people, the people of our state are here. Defending Ukraine for 100 days already," he said.

"Victory will be ours," he declared in a show of defiance in the video with the presidential office building as a backdrop.

Putin's troops are now concentrating their forces in the Donbas, in the east, where some of the fiercest fighting is centred on the industrial hub city of Severodonetsk.

Fighting continues in Severodonetsk's city centre, the president's office said, adding that the Russians were "shelling civilian infrastructure and Ukrainian military".

Severodonetsk "is the toughest area at the moment," Zelensky said late Thursday.

"For 100 days, they have been levelling everything", Lugansk regional governor Sergiy Gaiday said on Telegram.

Accusing the Russians of destroying hospitals, schools and roads, Gaiday said, however, that "we are only getting stronger.

"Hatred of the enemy and faith in our victory make us unbreakable."

Ukrainian troops were still holding an industrial zone, Gaiday said, a situation reminiscent of Mariupol, where a steelworks was the south-eastern port city's last holdout until Ukrainian troops finally surrendered in late May.

The situation in Lysychansk -- Severodonetsk's twin city, which sits just across a river -- also looked increasingly dire.

About 60 per cent of infrastructure and housing had been destroyed, while internet, mobile network and gas services had been knocked out, said the city's mayor Oleksandr Zaika.

"The shelling is getting stronger every day," he said.

In the city of Sloviansk, about 80 kilometres (50 miles) from Severodonetsk, the mayor has urged residents to evacuate as bombing intensified and water and electricity are cut off.

IN Mykolaiv in the south, Russian shelling killed at least one person and injured several others, Ukrainian military officials said late Thursday.