Russia has made minor advances in some areas since shifting its focus to fully occupying the Donbas, the UK's Ministry of Defence tweeted in a regular bulletin on Monday.
"Without sufficient logistical and combat support enablers in place, Russia has yet to achieve a significant breakthrough," it said.
Ukraine's defence of Mariupol has also exhausted many Russian units and reduced their combat effectiveness, British military intelligence said.
Reuters could not immediately verify the report.
(Reporting by Rachna Dhanrajani in Bengaluru; Editing by Christopher Cushing)
