Russia has probably suffered heavy losses as its forces retreated from the strategically important eastern Ukrainian town of Lyman, according to British military intelligence.
The town in the Donetsk region was "likely being defended by undermanned elements of Russia's Western and Central Military Districts as well as contingents of voluntarily mobilized reservists," the British Defence Ministry's daily brief said on Sunday.
"The force probably experienced heavy casualties as it withdrew along the only road out of the town still in Russian hands," it continued.
Russia abandoned the town of Lyman on Saturday in a bitter defeat to the Ukrainian army. Just a day earlier, Moscow declared it had annexed the Ukrainian region, a move declared illegal by the UN.
Lyman is a rail hub and features a key road crossing over the Donets river, "behind which Russia has been attempting to consolidate its defences," the intelligence update said.
According to the Russian military, the forces withdrew because of the risk of encirclement. Earlier, Ukrainian authorities had spoken of about 5,000 trapped Russian soldiers. There has been no concrete information on the number of casualties or possible prisoners of war.
The withdrawal triggered a wave of public criticism of the military leadership in Russian government circles, the British said.
"Further losses of territory in illegally occupied territories will almost certainly lead to an intensification of this public criticism and increase the pressure on senior commanders."
The British Ministry of Defence has been publishing daily information on the course of the war. Moscow accuses London of a targeted disinformation campaign.
