Most of Sievierodonetsk has fallen to Russia, says governor of Luhansk

Mayor of besieged Ukrainian city tells residents to stay in cellars as Russian forces advance block by block'

• Russia-Ukraine war: latest updates

Russian forces have taken control of most of the eastern city of Sievierodonetsk but have not surrounded it, the governor of Ukraine's Luhansk province has said as heavy fighting continued in and around the key city and civilians were told to stay underground.

Serhiy Gaidai said in an online post late on Tuesday that Russian shelling had made it impossible to deliver humanitarian supplies or evacuate people.