(Reuters) - Russia's offensive in Ukraine's Donbas region "has lost momentum and fallen significantly behind schedule", British military intelligence said early on Sunday.

       "Under the current conditions, Russia is unlikely to dramatically accelerate its rate of advance over the next 30 days," the British military said in a regular Twitter bulletin.

       On Friday, Ukrainian forces prevented an attempted Russian river crossing in the Donbas, an eastern area comprising the Luhansk and Donetsk regions that has been a focus of the war.

       (Reporting by Jaiveer Singh Shekhawat in Bengaluru; Editing by William Mallard)