Britain says Russia tries to encircle Ukraine positions in east

- Russia is probably attempting to encircle heavily fortified Ukrainian positions in the country's east, the British military said in an update on Tuesday.

Reports say the city of Kreminna has fallen, with heavy fighting in the south of the city of Izium, as Russian forces try to advance towards the cities of Sloviansk and Kramatorsk, Britain's defence ministry said on Twitter.

"Ukrainian forces have been preparing defences in Zaporizhzhia in preparation for a potential Russian attack from the south," it added in the regular bulletin.

Reuters could not immediately verify the report.