British Prime Minister Boris Johnson has met Ukrainian President Volodymyr Zelenskyy in Kyiv and promised further military assistance.

Johnson made the visit without prior notice to media on Saturday. Zelenskyy greeted him in English.

The British Prime Minister's Office says Johnson set out new military assistance of 120 armored vehicles and new anti-ship missile systems.

This is in addition to about 130-million-dollars' worth of military support Johnson announced on Friday.

In a video message released after the meeting, Johnson described what Russian President Vladimir Putin has done in places like Bucha and Irpin as war crimes.

He said the retreat of Russian forces is tactical and Putin is going to intensify the pressure now in Donbas and in the east.

Zelenskyy expressed his gratitude for the UK's support. He also urged Britain and other countries to intensify sanctions on Russia and to ban energy imports from Russia totally.

Johnson walked around the city with Zelenskyy and told those he met on the street that Britain will support the Ukrainian people.

His visit is viewed as a show of solidarity with Ukraine following a similar visit by European Commission President Ursula von der Leyen and EU foreign policy chief Josep Borrell on Friday.