Vladimir Putin’s forces are abducting Ukrainian politicians, activists and journalists as Russia fails to meet its military objectives, Foreign Secretary Liz Truss said.

She condemned the “abhorrent tactic” following work by Ukrainian human rights group ZMINA, which claimed to have identified dozens of individuals who had been abducted, with thousands more deported to Russia.

Ms Truss said Mr Putin was resorting to “desperate measures” as British military analysts said Russia’s invasion had suffered from a lack of momentum, poor logistics and low morale.

The Foreign Secretary said: “Putin continues to use abhorrent tactics against the Ukrainian people, including abducting innocent civilians.

“He is not achieving his objectives and is resorting to desperate measures.

“Putin must fail in Ukraine.”

Ms Truss, in a statement to the House of Commons, later told MPs: “We know that Putin is not serious about talks, he is still wantonly bombing innocent citizens across Ukraine and that is why we need to do more to ensure that he loses and we force him to think again.

“We must not just stop Putin in Ukraine but we must also look to the long term. We need to ensure that any future talks don’t end up selling Ukraine out or repeating the mistakes of the past.”

ZMINA’s chief Tetiana Pechonchyk said: “Russia is detaining and disappearing civilians in an attempt to break the spirit of the Ukrainian people.

“Today we are publishing our first list of those who have been taken so the Kremlin knows the world is watching and will not allow them to come to harm.

“In total we have so far documented 39 cases of enforced disappearances and arbitrary detentions in the Ukrainian territories newly occupied by Russia.”

Ukraine’s president Volodymyr Zelensky has signalled he is 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 Mr Putin “must fail”.

Mr Johnson and Mr Zelensky “shared information about the peace talks” in a phone call on Monday.

The two leaders also “discussed strengthening sanctions against Russia” and defence co-operation between the UK and Ukraine, Mr Zelensky said.

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 Prime Minister’s official 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:

– Chelsea owner Roman Abramovich was among a group of three people involved in Russia-Ukraine peace talks on March 3-4 who experienced symptoms of chemical weapons poisoning, investigative website Bellingcat reported.

– 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 refugees fleeing the fighting.

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”.