“The conflict in Ukraine is taking a heavy toll on some of Russia’s most capable units and most advanced capabilities,” UK Defence Intelligence said.
“It will take considerable time and expense for Russia to reconstitute its armed forces following this conflict,” it said, warning sanctions on advanced components would make it harder for Russia to re-arm.
The west, meanwhile, is stepping up arms deliveries to Ukraine’s defenders.
US President Joe Biden on Friday announced another package of military assistance worth US$150 million, including counter-artillery radars used for detecting the source of enemy fire.
This brings the total value of US weaponry sent to Ukraine since the Russian invasion began to US$3.8 billion.
Biden had urged Congress to approve a further US$33 billion package, including US$20 billion in military aid, “to strengthen Ukraine on the battlefield and at the negotiating table”.
The G7 leaders, including Biden, and Ukraine’s President Volodymyr Zelensky are to meet in a video conference on Sunday to discuss Western support for Kyiv.
On Friday, Zelensky said “diplomatic options” were also under way to rescue Ukrainian soldiers from the Mariupol steelworks, as civilian evacuations continued.
The Russian defence ministry said 50 people were evacuated from the site, including 11 children.
It added they were handed over to the UN and Red Cross, which are assisting in the operation, and that the “humanitarian operation” would continue on Saturday.
About 200 civilians, including children, are thought to be trapped in the tunnels and bunkers beneath Azovstal, along with Ukrainian soldiers making their last stand.
Russia announced a day-time ceasefire at the plant for three days starting Thursday but the Ukrainian army said Russian “assault operations” had continued by ground and air.
Ukraine’s Azov battalion, leading the defence at Azovstal, said one Ukrainian fighter had been killed and six wounded when Russian forces opened fire during an attempt to evacuate people by car.
RUSSIA TO REMAIN “FOREVER”
Since failing to take Kyiv early on in the war, Russia has refocused its offensive on the south and east of Ukraine.
Taking full control of Mariupol would allow Moscow to create a land bridge between the Crimean peninsula, which it annexed in 2014, and separatist, pro-Russian regions in the east.
In those regions, separatists said they had removed Ukrainian and English language traffic signs for Mariupol and replaced them with Russian ones.
Locals want to see proof that “Russia has come back here forever,” said Denis Pushilin, head of the breakaway region of Donetsk.
In neighbouring Lugansk, Ukrainian officials said on Friday that Russian forces had almost encircled Severodonetsk – the easternmost city still held by Kyiv – and are trying to storm it.
Kherson in the south remains the only significant city Russia has managed to capture since the war began.
A senior official from the Russian parliament visiting the city on Friday also emphasised that Russia would remain in southern Ukraine “forever”.
“There should be no doubt about this. There will be no return to the past,” Andrey Turchak said.
As European countries have sought to clamp down on Russian assets overseas, Italian authorities impounded a mega yacht as speculation swirled it might even belong to the Russian president.
“Scheherazade” is worth an estimated US$700 million. Financial police have been able to “establish significant economic and business links” between the owner and “eminent people in the Russian government”.
Researchers at the anti-corruption foundation of Russian dissident Alexei Navalny have linked the yacht to Putin.