Ukrainian President Volodymyr Zelenskyy said Russian forces were leaving behind “a complete disaster” as they retreat from the north, including towns just outside Kyiv, and he warned residents to beware of more Russian shelling and of land mines.

“There are a lot of trip wires, a lot of other dangers.”

He urged residents to wait to resume their normal lives until they are assured the mines have been cleared and the danger of shelling has passed.

He issued the warning as the humanitarian crisis in the encircled city of Mariupol deepened, with Russian forces blocking evacuation operations for the second day in a row, and the Kremlin accused the Ukrainians of launching a helicopter attack on a fuel depot on Russian soil.

Ukraine denied responsibility for the fiery blast, but if Moscow’s claim is confirmed, it would be the war’s first known attack in which Ukrainian aircraft penetrated Russian airspace.

Russia continued withdrawing some of its ground forces from areas around Kyiv after saying earlier this week it would reduce military activity in Kyiv and Chernihiv.

Ukraine recaptures more territory around Kyiv

Ukraine recaptured more territory around Kyiv from Russian soldiers who left shattered villages and their own abandoned tanks as they moved away from the capital.

In the hamlet of Dmytrivka, to the west of the capital, smoke was still rising from the wrecks of tanks and the bodies of at least eight Russian soldiers lay in the streets, according to Reuters correspondents.

“From one side we were hearing the tanks shooting at us, and from the area of Bucha was a massive mortar shelling,” said resident Leonid Vereshchagin, a business executive, referring to a town to the north.

Ukrainian forces went on to take back Bucha, its Mayor said on Friday in a video that appeared to be filmed outside the town hall.

The advances followed several days of Ukrainian gains around Kyiv and in the north.

In south-west Ukraine, anti-aircraft defences thwarted an attempted attack on critical infrastructure in the Black Sea port of Odesa, the Ukrainian military said. The account could not be immediately verified.

Odesa’s Governor, Maksym Marchenko, said three missiles had hit a residential district, causing casualties.

He said the missiles were fired from an Iskander missile system in Crimea, the southern Ukrainian peninsula annexed by Russia in 2014.

Ukraine prepares for assault in east

President Volodymyr Zelenskyy said on Thursday that Ukrainian forces were preparing for new Russian attacks in the south-east, where Moscow’s guns were now trained after its assault on the capital Kyiv was repelled.

In an early morning video address, Mr Zelenskyy said Russian troop movements away from Kyiv and the northern city of Chernihiv were “the consequence of our defenders’ work”.

But Ukraine was seeing “a build-up of Russian forces for new strikes on the Donbas and we are preparing for that”, he said, referring to the south-eastern region Russia demands Ukraine cede to separatists, where Mariupol is the main port.

Tough resistance by Ukrainian forces has so far prevented Russia from capturing any major city, including Kyiv, which it assaulted with armoured columns from the north-west and east.

US and European officials said Mr Putin was misled by his generals about the dire performance of Russia’s military.

Moscow says it is scaling back its offensives near the capital and the north and now focusing on “liberating” Donbas.

Mariupol, once a city of 400,000 people, has been destroyed by four weeks of relentless bombardment and siege.

The United Nations believes thousands of people have died there.

In a part of the city held by Russia, a man named Pavel placed a bowl and spoon as a tribute on a makeshift grave in a patch of grass, marked with a plain wooden cross.

The International Committee of the Red Cross (ICRC) said it was bringing a convoy of aid to reach the besieged city, where tens of thousands of people have been trapped for weeks under bombardment without food, water or heat.

Previous attempts to bring aid into besieged parts of the city have failed and civilians have only been able to escape if they have cars.

Ukraine said 45 buses were on their way on Thursday and the ICRC said it would evacuate civilians from Friday if the warring parties agreed on safe passage.

“It’s desperately important that this operation takes place,” said ICRC spokesperson Ewan Watson in Geneva.