in an update, the MoD said: “Russia has likely suffered devastating losses amongst its mid and junior ranking officers in the conflict. Brigade and battalion commanders likely deploy forwards into harm’s way because they are held to an uncompromising level of responsibility for their units’ performance.

"Similarly, junior officers have had to lead the lowest level tactical actions, as the army lacks the cadre of highly trained and empowered non-commissioned officers (NCOs) who fulfil that role in Western forces.

“The loss of large proportion of the younger generation of professional officers will likely exacerbate its ongoing problems in modernising its approach to command and control.

Ukraine conflict: Eurovision trophy sold to raise funds for the war in Ukraine

"More immediately, battalion tactical groups (BTGs) which are being reconstituted in Ukraine from survivors of multiple units are likely to be less effective due to a lack of junior leaders.”

It added: “With multiple credible reports of localised mutinies amongst Russia’s forces in Ukraine, a lack of experienced and credible platoon and company commanders is likely to result to a further decrease in morale and continued poor discipline.”

The Ukrainian military said the Russian forces were reinforcing their positions on the north-eastern and south-eastern outskirts of Sievierodonetsk and bringing additional equipment and ammunition into the area to press their offensive.

The Ukrainian army reported heavy fighting around Donetsk, the provincial capital, as well as Lyman to the north, a small city that serves as a key rail hub in the Donetsk region.

Ukraine conflict: Russia suffers 'devastating losses amongst mid and junior ranking officers' says MoD