The Kyiv city council is telling residents to prepare for heavy fighting in the Obolonsk area north of the city.
“Be vigilant and stay indoors – at home or in shelters. Going outside is very dangerous now due to the approaching enemy,” it says in an alert on Facebook.
Separately, the Ukrainian Interior Ministry has sent out information on how to make firebombs for citizens willing to resist invading Russian forces.
In Kharkiv, residents are being told to go to shelters as air raid sirens are reportedly followed by loud explosions.