Vladimir Putin’s invasion of Ukraine must end in failure, Downing Street said, as Volodymyr Zelensky signalled he was prepared to offer a series of concessions to Russia to end the fighting.

Ukraine could declare neutrality and offer guarantees about its non-nuclear status as part of a peace deal, Mr Zelensky suggested, but he stressed the desire to ensure the country’s “territorial integrity” – stopping the Kremlin from carving it up.

Downing Street said the UK would support Ukraine’s negotiating position but Boris Johnson firmly believes that Russian president Mr Putin “must fail”.

The PM was speaking to Mr Zelensky again on Monday, Downing Street said.

Mr Johnson’s official spokesman, speaking while the call was ongoing, said: “The Prime Minister provided an update on the supply of defensive lethal aid and also received an update on negotiations as well.”

He said: “Obviously, he updated that negotiations were ongoing and they discussed the importance of holding Putin to account for his actions rather than just his words.”

Earlier, the Government distanced itself from US President Joe Biden’s suggestion that Mr Putin “cannot remain in power” – an unscripted comment the White House was forced to row back on, insisting he was not calling for regime change in the Kremlin.

The spokesman said Mr Johnson “believes that Putin must fail in Ukraine and the sovereignty of Ukraine must be restored” ahead of the latest round of scheduled talks between the two sides’ negotiators on Tuesday.

“Obviously it would be for President Zelensky and the Ukrainian government to decide on the right approach to negotiations. We will support them in that,” the spokesman said.

“But it is not for the UK or any other country to seek to impose its will on the Ukrainian government as to what it should accept in those negotiations.”

In response to Mr Biden’s comments, the spokesman said: “It is up to the Russian people who should be governing them.”

Labour leader Sir Keir Starmer told LBC that Mr Biden’s comments were “not helpful”.

Cabinet minister Nadhim Zahawi, joking about the role of “education tsars” in his own department during a visit to a London school, said: “There’s one tsar I would like to get rid of now – but that’s up to the Russian people.”

In other developments:

– The Home Office has now granted 21,600 visas to Ukrainians with family links in the UK.

– Leading war crimes lawyer Sir Howard Morrison QC will act as an independent adviser to Ukrainian prosecutor general Iryna Venediktova.

– The Cabinet Office issued guidance to public sector bodies urging them to check if they have contracts with Russian or Belarusian companies and cancel them if possible.

– The UK and Australia announced joint plans to supply humanitarian aid to help refugees fleeing the fighting.

Foreign Secretary Liz Truss will update MPs on the latest situation in a Commons statement on Monday afternoon.

British defence intelligence analysts said on Monday that Russia has gained most ground in southern Ukraine, in the vicinity of Mariupol where heavy fighting continued as Mr Putin’s forces attempts to capture the strategically important port.

But the Ministry of Defence said logistical shortages, a lack of momentum and low morale were hitting the Russian invaders, combined with “aggressive fighting by the Ukrainians”.