Moscow signalled on Friday it was scaling back its ambitions in Ukraine to focus on territory claimed by Russian-backed separatists in the East as Ukrainian forces went on the offensive to recapture towns outside the capital Kyiv.

In an announcement that appeared to indicate more limited goals, the Russian Defence Ministry said a first phase of its operation was mostly complete and it would now focus on the eastern Donbass region, which has pro-Russia separatist enclaves.

"The combat potential of the Armed Forces of Ukraine has been considerably reduced, which ... makes it possible to focus our core efforts on achieving the main goal, the liberation of Donbass," said Sergei Rudskoi, head of the Russian General Staff's Main Operational Directorate.

Reframing Russia's goals may make it easier for President Vladimir Putin to claim a face-saving victory, military analysts said. Moscow had said its goals included demilitarising Ukraine. Western officials dismiss this as a baseless pretext for a war they say is aimed at toppling Ukraine's government.

Facing stiff resistance, Russian troops have failed to capture any major city in the month since invading Ukraine. Instead, they have bombarded cities, laid waste to urban areas and driven a quarter of Ukraine's 44 million people from their homes.

More than 3.7 million of them have fled abroad, half to neighbouring Poland, where U.S. President Joe Biden met soldiers from the U.S. Army's 82nd Airborne Division bolstering the NATO alliance's eastern flank.

"Hundreds of thousands of people are being cut off from help by Russian forces and are besieged in places like Mariupol," Biden said, referring to the besieged southeastern port.

"It's like something out of a science fiction movie."

Battlelines near Kyiv have been frozen for weeks with two main Russian armoured columns stuck northwest and east of the capital. A British intelligence report described a Ukrainian counter-offensive that had pushed Russians back in the east.

"Ukrainian counter-attacks, and Russian forces falling back on overextended supply lines, have allowed Ukraine to reoccupy towns and defensive positions up to 35 km east of Kyiv," the report said. Both the United States and Britain have given Ukraine arms.

'UNPREPARED TROOPS'

Russia's defence ministry said 1,351 Russian soldiers had been killed 3,825 wounded, the Interfax news agency reported. Ukraine says 15,000 Russian soldiers have died.

Volodymyr Borysenko, mayor of Boryspol, an eastern suburb where Kyiv's main airport is located, said 20,000 civilians had evacuated the area, answering a call to clear out so Ukrainian troops could counter-attack.

Ukrainian forces recaptured a nearby village the previous day and would have pushed on but halted to avoid putting civilians in danger, Borysenko said.

On the other main front outside Kyiv, to the capital's northwest, Ukrainian forces have been trying to encircle Russian troops in the suburbs of Irpin, Bucha and Hostomel, reduced to ruins by heavy fighting.

In Bucha, 25 km (15 miles) northwest of Kyiv, a small group of Ukrainian troops armed with anti-tank missiles was digging foxholes. A Ukrainian soldier who identified himself only as Andriy told Reuters he enlisted as soon as the invasion began.

"I told my wife to grab the children and to hide in the basement, and I went to the drafting station and joined my unit straight away," he said.

In the Vinnytsia area west of Kyiv, the Ukrainian Air Force said Russian cruise missiles hit several buildings while attempting to strike the Air Force's command in the area.

The United Nations said it had confirmed 1,081 civilian deaths and 1,707 injuries in Ukraine since the Feb. 24 invasion, adding that the real toll was likely higher.

Mariupol, a city of 400,000 before the war, has been among the worst hit by the Russian bombardment. Tens of thousands of people are still believed to be trapped with little access to food, power or heat.

Local officials, citing witness accounts, said they estimated that 300 people were killed in the bombing of a theatre in Mariupol on March 16. The city council had not previously provided a toll and made clear it was not possible to determine an exact figure after the incident. Russia has denied bombing the theatre.

The governor of Ukraine's Donetsk region, Pavlo Kyrylenko, said Ukrainian forces still controlled Mariupol. Around 65,000 people had fled but efforts to organise mass evacuations under ceasefires had mostly failed.

The cities of Chernihiv, Kharkiv and Sumy in the east have also endured devastating bombardment. Chernihiv was effectively surrounded by Russian forces, its governor said.

CULTURE WAR?

Weeks of on-and-off peace talks have failed to make significant progress. In a video address late Friday, Ukrainian President Volodymyr Zelenskiy said his troops' resistance had dealt Russia "powerful blows".

"Our defenders are leading the Russian leadership to a simple and logical idea: we must talk, talk meaningfully, urgently and fairly," Zelenskiy said.

Western sanctions have isolated Russia from global trade. President Vladimir Putin accused the West of trying to "cancel" Russian culture, including composers Pyotr Tchaikovsky and Sergei Rachmaninov, comparing it to actions by Nazi Germany in the 1930s.

China is the biggest power not to have condemned the Russian invasion and has repeatedly voiced opposition to the sanctions.

But in the first big sign that Western sanctions on Moscow were hurting investment from China, sources said state-run Sinopec Group, Asia's biggest oil refiner, halted talks on a petrochemical investment and a venture to market Russian gas.

"Companies will rigidly follow Beijing's foreign policy in this crisis," said an executive at a Chinese state oil company. "There's no room whatsoever for companies to take any initiatives in terms of new investment."