Russian forces pulling back from Ukraine’s capital region are creating a “catastrophic” situation for civilians by leaving mines around homes, abandoned equipment and “even the bodies of those killed”, President Volodymyr Zelensky has warned.

Ukraine and its western allies reported mounting evidence of Russia withdrawing its forces from around Kyiv and building up troop strength in eastern Ukraine.

Ukrainian fighters reclaimed several areas near the capital after forcing the Russians out or moving in after them, officials said.

The visible shift did not mean the country faced a reprieve from more than five weeks of war or that the more than four million refugees who have fled Ukraine will return soon.

Mr Zelensky said he expects departed towns to suffer air strikes and shelling from distance, and for the battle in the east to be intense.

“It’s still not possible to return to normal life, as it used to be, even at the territories that we are taking back after the fighting,” he told the nation in a nightly video message.

“We need wait until our land is de-mined, wait till we are able to assure you that there won’t be new shelling.”

Moscow’s focus on eastern Ukraine also kept the besieged southern city of Mariupol in the crosshairs.

The port city on the Sea of Azoz is located in the mostly Russian-speaking Donbas region, where Russia-backed separatists have fought Ukrainian troops for eight years and military analysts think Russian President Vladimir Putin is seeking to expand control after his forces failed to secure Kyiv and other major cities.

The International Committee of the Red Cross is planning to try to get emergency supplies into Mariupol and to evacuate residents.

The ICRC said it was unable to carry out the operation on Friday because it did not receive assurances the route was safe. City authorities said the Russians blocked access to the city.

Mariupol, which was surrounded by Russian forces a month ago, has been the scene of some of the war’s worst attacks, including on a maternity hospital and a theatre sheltering civilians.

Around 100,000 people are believed to remain in the city, down from a pre-war population of 430,000, and they are facing dire shortages of water, food, fuel and medicine.

The city’s capture would give Moscow an unbroken land bridge from Russia to Crimea, which it seized from Ukraine in 2014, but also has taken on symbolic significance during Russia’s invasion, said Volodymyr Fesenko, head of Ukrainian think tank Penta.

“Mariupol has become a symbol of Ukrainian resistance, and without its conquest, Putin cannot sit down at the negotiating table,” he said.

Mariupol city council said on Saturday that 10 empty buses were heading to Berdyansk, a city 84 kilometres west of Mariupol, to pick up people who can get there on their own.

Some 2,000 made it out of Mariupol on Friday, some on buses and some in their own vehicles, city officials said.

An adviser to Mr Zelensky, Oleksiy Arestovych, said in an interview with a Russian lawyer and activist, Mark Feygin, that Russia and Ukraine had reached an agreement to allow 45 buses to drive to Mariupol to evacuate residents “in coming days”.

Such agreements have been reached before, only to be breached. On Thursday, Russian forces blocked a 45-bus convoy attempting to carry people out of Mariupol and seized 14 tons of food and medical supplies bound for the city, Ukrainian authorities said.

Mr Zelensky said he discussed the humanitarian disaster in Mariupol with French President Emmanuel Macron by telephone and with the president of the European Parliament, Roberta Metsola, during her visit to Kyiv on Friday.

“Europe doesn’t have the right to be silent about what is happening in Mariupol,” Mr Zelensky said. “The whole world should respond to this humanitarian catastrophe.”

On the outskirts of Kyiv, signs of fierce fighting were everywhere after the Russian redeployment, with destroyed armoured vehicles from both armies left in streets and fields and scattered military gear covering the ground next to an abandoned Russian tank.

Ukrainian forces recaptured the city of Brovary, 20 kilometres east of the capital, mayor Ihor Sapozhko said in a televised address. Shops were reopening and residents were returning but “still stand ready to defend” their city, he added.

“Russian occupants have now left practically all of the Brovary district,” he said. “Tonight, (Ukrainian) armed forces will work to clear settlements of (remaining) occupants, military hardware, and possibly from mines.”

Elsewhere, at least three Russian ballistic missiles were fired late on Friday at the Odesa region on the Black Sea, regional leader Maksim Marchenko said. The Ukrainian military said the Iskander missiles did not hit the critical infrastructure they targeted.

Odesa is Ukraine’s largest port and the headquarters of its navy.

There was no immediate word on the latest round of talks between Russian and Ukrainian negotiators, which took place on Friday by video link.

During a round of talks earlier in the week, Ukraine said it would be willing to abandon a bid to join Nato and declare itself neutral — Moscow’s chief demand — in return for security guarantees from several other countries.

On Friday, the Kremlin accused Ukraine of launching a helicopter attack on a fuel depot on Russian soil.

Ukraine denied responsibility for the fiery blast at the civilian oil storage facility on the outskirts of the city of Belgorod, about 25 kilometres from the Ukraine border.

If Moscow’s claim is confirmed, it would be the war’s first known attack in which Ukrainian aircraft had penetrated Russian air space.

Later, in an interview with American TV channel Fox News, Mr Zelensky refused to say whether Ukraine was behind the attack.