Regional leaders said the Ukrainian army may have to “withdraw” to stronger positions in the eastern city of Severodonetsk, amid heavy fighting in the city and villages on the frontline in the south where Russia seeks a breakthrough in the Donbass.

Serhiy Hayday, the governor of Luhansk, said the Russians were trying to capture the city by Friday, while the road from neighboring Lyschansk to Pakhmut, 30 miles southwest of the country, was being bombed too frequently to be used.

“The fighting is still going on and no one will give up the city even if our army has to retreat to stronger positions. This does not mean that someone is giving up the city – no one will give up anything. But it is possible. [they] He said in a TV interview.

But the governor insisted on his Telegram channel that he was not planning to back off. “Do not breed treason. Do not spoil the mood of the armed forces! No one will surrender to Severodonetsk!” He said, adding that the defenders of Ukraine would fight for “every inch”.

Ukrainian advisers say that Severodonetsk and Lesichansk are not strategic cities, and their goal is to weaken the Russian army by fighting hard for them. But it is the only remaining parts of Luhansk Territory not under Russian control.

Russia changed its invasion plan in April after its failed attempt to capture the major cities of Kyiv, Kharkiv, and Odessa. The focus shifted to Donbass, made up of the Luhansk and Donetsk regions, the latter of which is still under Ukrainian control.

“The Ukrainian group in Donbass suffered heavy losses in manpower, weapons and military equipment,” the Moscow Defense Ministry said, and said it had caused 480 casualties during the fighting in Donbass and elsewhere in the country during the night.

Ukraine’s President, Volodymyr Zelensky, said in his nightly update that Russia was trying to “attract additional resources in the Donbass” – arguing that Moscow should resort to reinforcements due to the strength of the resistance.

Britain’s Ministry of Defense said in its morning update that Russia was attacking Severodonetsk and the Ukrainian enclave behind it “from three directions”. “Ukrainian defenses are holding up,” she added, saying: “It is unlikely that either side has made significant gains in the past 24 hours.”

The Ukrainian military reported an increase in airstrikes, as well as heavy shelling and rocket and mortar shelling around Bakhmut, which aid agencies reported was becoming increasingly inaccessible to non-military traffic.

Both sides continue to suffer heavy losses, although accurate estimates are impossible to obtain. Ukrainian officials said 100 or even 150 people are killed every day in battle, while Zelensky said overnight that “Russia has been killing nearly 300 people a day” since it launched the invasion on February 24.

Fighting also continued around Mykolaiv as Ukraine continued to attempt limited counterattacks on the occupied city of Kherson. Russia said it shot down two MiG-29s and one Mi-8 helicopter in the area, as well as 11 drones.

Ukraine said Russia was trying to distribute passports in the occupied Kherson region, offering to pay 10,000 rubles (£132) as an incentive. The Kyiv Center for National Resistance said the same amount was given in the neighboring Zaporizhzhya region to collect “personal data” – but the “vast majority” of residents refuse to comply with the occupation administration.

Russia’s Foreign Minister, Sergei Lavrov, said the responsibility lies with Ukraine to resolve the issue of resuming grain shipments – halted due to the Black Sea naval blockade run by the Russian Navy – at a press conference on Wednesday with his Turkish counterpart Mevlut Cavusoglu.

“We announce daily that we are ready to ensure the safety of ships leaving Ukrainian ports and heading to the Bosphorus Gulf. To solve the problem, the only thing that is required is for the Ukrainians to allow the ships to leave their ports, either by clearing mines or by designating safe passages.”

Ukraine says it does not trust the Russians and does not intend to try to open its ports except as part of a broader international agreement. Meanwhile, a Russian news agency reported that 11 grain carts taken from Ukrainian silos in the areas occupied by the Moscow force were transferred to the Crimea.

On Tuesday, Russian Defense Minister Sergei Shoigu announced the opening of a road corridor between Russia and Crimea, passing through the Ukrainian territory occupied since February 24. The port of Mariupol, which was the scene of the fiercest fighting earlier in the war, was now demined, and cargo ships were arriving.