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