Humanitarian charity says thousands of civilian lives in danger if they remain in besieged port city

Ukraine has launched a fresh attempt to rescue civilians from Mariupol after warnings from the Red Cross that thousands of lives depend on the successful evacuation of people trapped in the besieged city by Russian forces.

A total of 45 buses were en route to the nearby southern coastal town of Berdyansk, the Ukrainian deputy prime minister, Iryna Vereshchuk, said, along with a team from the International Committee of the Red Cross (ICRC) delivering humanitarian aid and assisting evacuations. The convoy was expected to enter the city on Friday morning after Russian promises of a limited ceasefire along the route from Mariupol to the Ukraine-held city of Zaporizhzhia.

Repeated efforts to set up humanitarian corridors for the evacuation of up to 170,000 people who remain in Mariupol, which has suffered four weeks of bombardment and dwindling supplies, have failed. Ukraine has accused Russian forces of shelling supposedly safe routes outside of several fighting hotspots; claims that Moscow denies.

“Time is running out to help these people. This evacuation is hugely important,” said Alyona Synenko, a spokesperson for the ICRC. “It is essential we get concrete and precise agreements from both sides on times and routes tomorrow. These instructions need to be conveyed to military units on the ground and they must be respected.

“We distributed the last of the supplies we had there two weeks ago. People have nothing now. We are ready to help and we are hoping tomorrow safe passage materialises.”

Control of Mariupol, a strategic port once home to 400,000 people and still in the Ukrainian government’s hands, would ensure Russian dominance in the inland Sea of Azov.

Together with self-proclaimed republics in Luhansk and Donetsk and other eastern territories seized recently by Russia, it would create a land corridor from the Russian mainland to Crimea. As such, it has been a major focus of Moscow’s five-week offensive and civilians there have suffered gravely. The Ukrainian president, Volodymyr Zelenskiy, said on Friday that at least 5,000 people had died in the assault on Mariupol.

Water, food and medicine are running low, and many families have been unable to bury loved ones killed by airstrikes and shelling because of the ferocity of the Russian attack. A maternity hospital, an arts centre housing displaced people and a Red Cross warehouse have all been struck, while residents who have managed to find fuel and undamaged cars have taken their lives into their own hands to flee.

A successful evacuation on Friday morning would greatly improve the chance of progress in peace talks, which are also planned to resume online tomorrow. By the same token, if the humanitarian corridor was again attacked, the prospect of any major breakthrough would diminish.

Ukraine and its western allies remain sceptical of Moscow’s overtures, which appear to include troop withdrawals from some areas of the country to focus on “liberating” the eastern region.

On Thursday, Ukraine’s state nuclear company said most of the Russian forces that had occupied the Chernobyl nuclear power station since soon after the 24 February invasion had set off towards the Belarus border, with only a small number remaining. Russian forces have also withdrawn from the nearby town of Slavutych, where power station workers live.

Despite the claims of a wider drawdown earlier this week, Russian forces have continued to bombard the northern city of Chernihiv, while the area’s governor, Viacheslav Chaus, said Russian troops were on the move but may not be withdrawing.

“The enemy is taking losses. It is moving in the territory of Chernihiv region. Can we call that a withdrawal of troops? I am not sure. At the minimum, it is regrouping, but it is possible that it is withdrawing. We must not let down our guard,” he wrote on the messaging app Telegram.

Ukrainian officials said there had been artillery barrages in and around the north-eastern city of Kharkiv over the past day, and heavy fighting had continued in several suburbs of the capital, Kyiv, where Ukrainian forces have counterattacked.

Unverified pictures and video which emerged on Thursday on a Kharkiv news channel on Telegram showed massive damage caused by Russian strikes on a large farm about 18 miles (30km) north-east of the city. Russia’s defence ministry also reported new strikes on Ukrainian fuel stores overnight.

An interior ministry adviser, Vadym Denysenko, said a corridor between two eastern towns – Izyum and Volnovakha – was becoming a key battlefront.

In another sign of Russian intent, the top rebel leader in Donetsk, Denis Pushilin, issued an order to set up a rival city government for Mariupol, according to Russian state news agencies.

Zelenskiy said on Thursday that the continued fighting confirmed Ukraine’s suspicions that Russia was using talk of de-escalation as cover to prepare its forces for a renewed offensive in eastern Ukraine.

Thousands of Ukranians and Russian soldiers have died and about 4 million Ukranians have fled the country since the Russian president, Vladimir Putin, announced a “special military operation” to disarm and “de-nazify” its neighbour.

In the face of fierce Ukrainian resistance, as well as substandard equipment and poor morale among Russian troops, however, Moscow has struggled to take control of any significant territory.

Western intelligence agencies have claimed that Putin’s advisers are afraid to tell him the truth about the stalled offensive and the extent of the damage to Russia’s economy caused by crippling international sanctions.