Russia attacks chemical plant in Ukraine's Severodonetsk city

Officials estimate that as many as 800 civilians are hiding in the plant

Russian shelling has caused a huge fire at a chemical plant in Ukraine's Severodonetsk city where "non-stop" fighting rages, the regional head says.

Serhiy Haidai told Ukrainian TV that Saturday's blaze started after a leak of tens of tonnes of oil from damaged radiators at the Azot plant.

Hundreds of civilians are reportedly sheltering at the plant.

Severodonetsk has become the focal point of Russia's efforts to advance in eastern Ukraine.

Fighting has lasted more than three months. Russia's early attempt to capture major cities including the capital Kyiv faltered and is now instead trying to capture the Luhansk and the Donetsk regions — a vast mostly industrial area collectively known as Donbas.

Seizing Severodonetsk and its twin city of Lysychansk would move Russia closer to its goal as it would give them control over Luhansk.

In his statement, Haidai admitted most of Severodonetsk was now in Russian hands. The Russian military says that all of Severodonetsk's residential areas are now under its control.

"The Azot chemical plant has been under heavy shelling for hours," Mr Haidai said on Saturday.

He did not say whether there were any casualties and whether the blaze was later extinguished.

Ukrainian officials estimate that as many as 800 civilians are hiding in underground bomb shelters at the Azot plant.

Describing the current situation in Severodonetsk, Mr Haidai said it was "difficult, but under control".

"Our soldiers are winning in street fights, but, unfortunately, the enemy's artillery is simply dismantling - floor-by-floor — the houses used by our troops as shelters.

"So, when we push the enemy out of one street, they start using their tanks and artillery to destroy the area house-by-house," the Luhansk regional head said.

"No one can say whether and how many victims there have been in the last 24 hours in Sievierodonetsk, where intense fighting continues," Gaidai said on the Telegram messaging app on Sunday.

Ukrainian President Volodymyr Zelensky said that Russian troops have suffered "very significant" casualties in Donbas.

He also said Ukrainian forces had recaptured villages and towns in the south-eastern regions of Kherson and Zaporizhzhia.

Ukraine has been pleading for more weapons from its allies, warning that Russia has at least 10 times more artillery pieces.

Russia is using its overmatch in force ratio and artillery to "gradually seize territory in and around Severodonetsk" from Ukrainian control, the UK's defence ministry says in its latest update.

It says Russia continues to seek to generate combat units to deploy to Ukraine. In recent weeks, Russia probably started preparing to deploy the third battalion from some combat formations, the ministry says, while most brigades normally only committed a maximum of two of their three battalions to operations at any one time.

Third battalions within brigades are often not fully staffed, the MOD notes, and Russia will probably have to rely on new recruits or mobilised reservists to deploy these units to Ukraine.

"Deploying all three of their battalions simultaneously will likely reduce formations’ longer term capacity to regenerate combat power after operations," the UK defence ministry says.

After being forced to scale back its initial campaign goals Moscow has turned to expanding control in the Donbas, where pro-Russian separatists have held a swathe of territory since 2014.

Russia destroys depot containing weapons from Europe and US

Russian forces fired cruise missiles to destroy a large depot containing US and European weapons in western Ukraine's Ternopil region, Interfax reported on Sunday. The governor of the Ternopil region said a rocket attack on the city of Chortkiv fired from the Black Sea had partly destroyed a military facility, injuring 22 people.

‘Don’t know how long the war will last; forces defying predictions’ 

Ukrainian President Volodymyr Zelenskyy said no one knows how long the war in his country will last but that Ukrainian forces are defying expectations by preventing Russian troops from overrunning eastern Ukraine, where the fighting has been fiercest for weeks. Zelenskyy said he was proud of the Ukrainian defenders managing to hold back the Russian advance in Donbas.

Russia using overmatch to seize Sieverodonetsk: UK

Russia is using its overmatch in force ratio and artillery to gradually seize territory in and around Ukraine's Sieverodonetsk, Britain's Defence Ministry said on Sunday. Russia has likely started preparing to deploy the third battalion from some combat formations in recent weeks, the ministry said in its latest intelligence update posted on Twitter.