A third United Nations operation is under way to evacuate civilians from the Azovstal steel plant in Mariupol. “A convoy is proceeding to get to Azovstal by tomorrow morning hopefully to receive those civilians remaining in that bleak hell … and take them back to safety,” the UN humanitarian chief, Martin Griffiths, said.

The UN secretary general, António Guterres, has described the war zone in Mariupol as appearing to be “hellscapes”. The UN and the International Committee of the Red Cross have so far helped nearly 500 civilians flee the steel plant area in the southern port city during two operations in the past week.

A Ukrainian commander said “heavy, bloody fighting” continues at Azovstal and Russia violated its promise of a ceasefire, preventing the evacuation of civilians. Svyatoslav Palamar, a commander of the Azov regiment that is defending the site, said in a video on Telegram: “Russians violated the promise of a truce and did not allow the evacuation of civilians who continue to hide from shelling in the basement of the plant.” Palamar earlier pleaded for help for the “wounded soldiers dying in terrible agony” and the evacuation of civilians trapped in the plant.

The Russian president, Vladimir Putin, demanded that Ukraine order its fighters holed up in Azovstal to surrender, the Kremlin said. In a call with Israel’s prime minister, Naftali Bennett, Putin claimed Russia was still ready to provide safe passage for civilians from the plant, according to the Kremlin.

Ukraine is “unlikely” to launch a counter-offensive before mid-June, when it hopes to have received more weapons from its allies, an adviser to the Ukrainian president, Volodymyr Zelenskiy, said. Oleksiy Arestovych added that he did not expect Russia’s offensive in Ukraine to produce any “significant results” by 9 May, when Russia celebrates its Victory Day over Nazi Germany.

The US says it shared intelligence with Ukraine about the location of the Russian missile cruiser Moskva prior to the strike that sank the warship, but the decision to attack was taken by the Ukrainians. US officials also reportedly confirmed they are providing intelligence that has helped Ukrainian forces target and kill many of the Russian generals.

Zelenskiy has reportedly invited the German chancellor, Olaf Scholz, and president, Frank-Walter Steinmeier, to visit him in Kyiv. Zelenskiy made the invitation during a telephone call with Steinmeier in which “past irritations were cleared up”, weeks after the president was snubbed by Ukraine, a source from the German president’s office said. Zelenskiy confirmed he had spoken with Steinmeier today.

The UK government has placed sanctions on Evraz, the multinational steelmaker part-owned by the billionaire Roman Abramovich. The company was formerly counted among Britain’s biggest companies. The Foreign Office said on Thursday that the action would “further chip away at Putin’s financial reserves and siege economy, and support Ukraine’s continued resistance”.

The European Union plans to impose sanctions on Alina Kabaeva, long rumoured to be Vladimir Putin’s girlfriend, and Patriarch Kirill, the head of the Russian Orthodox church. Two sources said the EU has proposed sanctions on Kabaeva, a former Olympic gymnast whose appearance on a draft sanctions list was first reported by Bloomberg.

Naftali Bennett said Vladimir Putin had apologised for the Russian foreign minister’s claims that Adolf Hitler had Jewish origins. The Israeli prime minister, after a call with Putin, said he had accepted the apology and thanked the president for clarifying his position.

Putin hopes to claim Mariupol as key prop in Victory Day celebrations, according to Ukrainian intelligence. “Mariupol, according to [Russia’s] plans, should become the centre of celebrations,” Ukraine’s defence intelligence agency said. “For this purpose, the city is urgently cleaning the central streets from rubble, bodies of dead and unexploded Russian ammunition. A large-scale propaganda campaign continues, during which Russians will be shown stories about the ‘joy’ of local residents from meeting with the invaders.”