British Red Cross executive director Zoe Abrams said the humanitarian network was “profoundly concerned” about the plans to “send traumatised people halfway round the world to Rwanda”.
“The financial and human cost will be considerable,” Ms Abrams said. "Evidence from where offshoring has been implemented elsewhere shows it leads to profound human suffering, plus the bill that taxpayers will be asked to foot is likely to be huge.
“We are not convinced this drastic measure will deter desperate people from attempting to cross the Channel, either.
"People come here for reasons we can all understand, like wanting to be reunited with loved ones or because they speak the language. Making it harsher may do little to stop them risking their lives.”
The House of Lords could oppose the measure, having already inflicted defeats on the Government’s Nationality and Borders Bill.
The legislation is in a tussle between the Commons and the Lords after peers defeated ministers, including with a demand that offshore asylum claims should be subject to approval by both Houses of Parliament.
Steve Valdez-Symonds, Amnesty International UK’s refugee and migrant rights director, said the “shockingly ill-conceived idea will go far further in inflicting suffering while wasting huge amounts of public money”.
Sonya Sceats, the chief executive of the Freedom from Torture charity, said plans to “imprison refugees in prison camps in Rwanda is deeply disturbing and should horrify anybody with a conscience”.
“It is even more dismaying that the UK government has agreed this deal with a state known to practise torture, as we know from the many Rwandan torture survivors we have treated over the years,” Ms Sceats said.
She suggested Mr Johnson was hoping the “cynical announcement will distract from his own lawbreaking and shore up his party’s plummeting support in the upcoming local elections”.
Ministers have been under pressure to accept more refugees fleeing Russia’s invasion of Ukraine, with the visa system criticised as too bureaucratic.
Enver Solomon, chief executive of the Refugee Council, urged the government to “immediately rethink its plans”.
“We are appalled by the Government’s cruel and nasty decision to send those seeking sanctuary in our country to Rwanda,” Mr Solomon said.
“Every day we are hearing the stories of desperate Ukrainian families fleeing war.
"This is the brutal reality faced by refugees escaping conflicts all over the world, who this government now wants to treat as no more than human cargo to be shipped elsewhere.
“Offshoring the UK’s asylum system will do absolutely nothing to address the reasons why people take perilous journeys to find safety in the UK.
“It will do little to deter them from coming to this country, but only lead to more human suffering and chaos – at a huge expense of an estimated £1.4bn a year.”
The expected deal with Rwanda comes after other locations suggested — including Ascension Island, Albania and Gibraltar — were rejected, at times angrily by the nations.
Updated: April 13, 2022, 10:39 PM