Russian forces are “struggling to conduct offensive operations” because of the “sustained Ukrainian resistance” they have faced since their unprovoked invasion, according to a UK military intelligence assessment.

       Vladimir Putin’s military has suffered such serious losses that Russia is “increasingly seeking to generate additional troops to bolster and replace its personnel losses in Ukraine,” the Ministry of Defence said in its latest update.

       “As a result of these losses it is likely that Russia is struggling to conduct offensive operations in the face of sustained Ukrainian resistance. Continues personnel losses will also make it difficult for Russia to secure occupied territory.”

       The assessment came as Kyiv residents entered a 35-hour curfew after Russian airstrikes and shelling killed dozens of people, as Russian troops continued on their mission to seize Ukraine’s capital city.

       The MoD added that Russia was having to draw extra forces from across its military to boost its forces in Ukraine as its attempts to topple the country appear to have bogged down.

       Recommended Ukraine news – live: Kyiv rejects proposed neutrality in peace talks Why has Russia invaded Ukraine? The conflict explained Sign The Independent’s petition to help the people of Ukraine

       “Russia is redeploying forces from as far afield as its Eastern Military District, Pacific Fleet and Armenia. It is also increasingly seeking to exploit irregular sources such as Private Military Companies, Syrian and other mercenaries,” the MoD tweeted.

       “Russia will likely attempt to use these forces to hold captured territory and free up its combat power to renew stalled offensive operations.”

       Recommended Three million people have now fled war in Ukraine, says UN Trump says a ‘lot of love’ behind Putin’s decision to invade Ukraine Biden’s approval rating holding steady as US warms to his Ukraine response, poll finds

       Earlier, the prime ministers of Poland, the Czech Republic and Slovenia traveled to the embattled Ukrainian capital of Kyiv and met with President Volodymyr Zelensky, despite Russian bombardment of the city.

       The three leaders went ahead with the hours-long train trip despite worries within the European Union about the security risks of traveling within a war zone.

       “It is here, in war-torn Kyiv, that history is being made. It is here, that freedom fights against the world of tyranny. It is here that the future of us all hangs in the balance,” tweeted Poland’s Prime Minister Mateusz Morawiecki.