Ukraine is ready to offer unconditional talks on Mariupol and has proposed a “special round” of negotiations with Russia in the besieged city, the Ukrainian negotiator and presidential aide Mykhailo Podolyak tweeted. Another key Ukrainian negotiator, David Arakhamia, said he and Podolyak were ready to arrive in Mariupol to hold talks and “a proposal was put forward to hold direct negotiations, on site, on the evacuation of our military garrison”.

Volodymyr Zelenskiy has said the situation in Mariupol is deteriorating with roughly 1,000 civilians remaining trapped in the Azovstal steel plant with the remaining fighters who are heavily outnumbered. The Ukrainian president said 120,000 people were being kept in Mariupol and that “crimes that are happening there are far more scary and large scale than in Borodyanka”, referencing another devastated Ukrainian town.

Ramzan Kadyrov, an ally of Vladimir Putin, said he believed Russian forces would be in complete control of the Azovstal steel plant in Mariupol “before lunchtime, or after lunch” on Thursday.

Finance ministers from the UK, US, Canada and France walked out of Wednesday’s G20 meeting as Russian representatives spoke, amid divisions over Russia’s continued presence in the body.

Intelligence indicates Russia is poised to launch powerful cyber-attacks against rivals supporting Ukraine, members of the “Five Eyes” intelligence sharing network – the US, Britain, Canada, Australia and New Zealand – have warned.

Ukraine is working to convince western allies to shift Russia’s shipments of natural gas from the Nord Stream 1 pipeline to Ukraine’s pipeline, increasing Kyiv’s leverage, energy officials told Reuters.

Italy has signed a deal with Angola to ramp up gas supplies in a bid to break away from Russian gas. In an interview with the Corriere della Sera, Italy’s prime minister, Mario Draghi, said: “We do not want to depend on Russian gas any longer, because economic dependence must not become political subjection.”

The US defence department has retracted its claim that Ukraine had been supplied with more aircraft, instead saying only parts had been delivered to enable Kyiv to put more jets into action. A senior US defence official said 14 US howitzers were being delivered, along with their ammunition.

Germany has defended itself against criticism of its delay in authorising the delivery of heavy weapons to Ukraine. The Bild newspaper reported the government dropped armoured vehicles and tanks from a list that German arms manufacturers were offering to make available to Ukraine – slashing the catalogue from 48 to 24 pages.

Zelenskiy spoke of his “cautious optimism” that Ukraine’s partners now better understand the needs of his country, seemingly in reference to supplying weapons and intensifying sanctions on Russia.

Ukraine can develop “maximum speed” in joining the EU, Zelenskiy said in a national address on Wednesday evening after meeting the president of the European Council, Charles Michel. He called it a “historic moment”.

Russia said it had test-launched its Sarmat intercontinental ballistic missile, a new addition to its nuclear arsenal. The Pentagon said the test was “routine” and not considered a threat.

The UK prime minister, Boris Johnson, likened Vladimir Putin to a crocodile, saying he is not optimistic that the Russian leader can be negotiated with. “How can you negotiate with a crocodile when it has your leg in its jaws, that is the difficulty that Ukrainians face. It is very hard to see how the Ukrainians can negotiate with Putin now given his manifest lack of good faith.”