Would-be sponsors under the Homes For Ukraine visa scheme are threatening the Government with legal action after a successful Marlow challenge.

A class action lawsuit is being prepared over “inordinate and unreasonable delays” in processing hundreds of visa applications made in March.

It comes as Prime Minister Boris Johnson admitted that refugees could have been helped to get to the UK faster.

Last week, The Marlow Ukraine Collective joined the protest outside the Houses of Parliament over problems with visa delays.

Figures compiled by would-be hosts, show there were at least 800 Ukrainian refugees still waiting for visas after applying in the first two weeks of the scheme opening.

The Marlow Ukraine Collective comprises of 45 host families who sponsor 123 Ukrainians, including 56 children but only 19 visas had been granted as April 22.

The groups behind the action say the delays have put people in Ukraine and border countries at risk.

Lawyers for the groups are planning to send a pre-action protocol letter to the Home Office this week, asking it to “sort out the endless muddles and tangles”.

They could then apply for a judicial review of the Government’s visa-processing policy.

The legal letter will highlight 10 cases of Ukrainians who are still waiting for their visas after applying during the days after the Homes For Ukraine scheme first opened on March 18.

The legal action is being prepared by Amanda Jones, an immigration and public law barrister.

Ms Jones succesfully challenged the Government on behalf of a Marlow Ukraine Collective member, who had been waiting more than a month to bring the family she is sponsoring to the UK.

Rebecca Lewis, a 44-year-old teacher from Marlow, Buckinghamshire, sought help after the mother she is sponsoring received her visa on April 9 but her children, aged four and five, were still waiting.

After Ms Jones contacted the Government, within nine hours the family was told the remaining visas were ready, she said.

Ms Jones said the judicial review would be brought on the grounds that the Home Office has a policy of delaying the March applications, and deciding later applications instead – or that the system is “so chaotic and unstable” that it is unreasonable.

She said hundreds of applications made during March remain outstanding, and those waiting are “running out of money, hope and support”.

A Government spokesman said: “In response to (Vladimir) Putin’s barbaric invasion we launched one of the fastest and biggest visa schemes in UK history. Over 86,000 visas have been issued so Ukrainians can live and work in the UK.

“The changes the Home Office has made to streamline the visa system, including simplifying the forms and boosting staff numbers, are working and we are now processing visas as quickly as they come in – enabling thousands more Ukrainians to come through our uncapped routes.”