Ministers could spend £169,000 on every asylum seeker forcibly removed to a third country such as Rwanda, according to the Home Office’s own estimates.

Nearly two in five people would need to be deterred from crossing the Channel in small boats for the Illegal Migration Bill to break even, the economic impact assessment published on Monday said.

Judges will hand down their judgment on the stalled Rwanda policy on Thursday as the Government desperately battles to fulfil its promise to “stop the boats”.

Suella Braverman visit to London charities
Home Secretary Suella Braverman promised the Bibby Stockholm accommodation barge would be in Portland by June 19 but it has not yet arrived (Yui Mok/PA)

Last year 45,755 people were detected to have made the perilous journey.

The Home Office document said the policy of relocating migrants to “safe third countries” could save between £106,000 and £165,000 per person.

However, it said the figures are “highly uncertain” and that the measures would need to deter 37% of people from crossing for the costs to be recouped.

The £169,000 cost includes flights and detention, as well as a £105,000 per person payment to third countries.

The sum is an estimate not based on the true cost of the “commercially sensitive” Rwanda scheme.

Despite Government efforts, Kigali is the only capital to have agreed to such a scheme with the UK.

Home Secretary Suella Braverman called for Parliament to support her legislation, arguing that the assessment “shows that doing nothing is not an option”.

“We cannot allow a system to continue which incentivises people to risk their lives and pay people smugglers to come to this country illegally, while placing an unacceptable strain on the UK taxpayer,” she said.

“I urge MPs and Peers to back the Bill to stop the boats, so we can crack down on people smuggling gangs while bringing our asylum system back into balance.”

General Election 2019
Liberal Democrat home affairs spokesman Alistair Carmichael said the plan was unworkable (Aaron Chown/PA)

The document said that the asylum system could cost £32 million a day by the end of 2026 if recent trends continue without the reduction of hotel usage.

The assessment said that it is “not possible to estimate with precision the level of deterrence” the Bill will have.

It noted that academic consensus is there is “little to no evidence” that policy changes deter people leaving their home countries and seeking refuge.

Instead, shared language, culture and family ties were accepted to be “strong factors” influencing choice of final destination.

The document said evidence from a variety of countries such as Australia gives a “stronger basis” to think a policy change in the UK could have an impact.

But it acknowledged asylum seekers may not be aware of UK law when making their journeys and may push on regardless because they consider the benefits to be larger than the risks.

The assessment process does not consider the potential cost of making further agreements to expand the scheme beyond Rwanda, while noting that its estimates for the cost of third-party schemes was based on an National Audit Office study of the cost of the UK’s Syrian Vulnerable Persons Resettlement Programme.

“It should not be considered to represent the actual cost of any current or future relocation agreement with a third country,” the assessment notes.

The Refugee Council, which criticised the assessment, pointed in particular to the assumption that individuals will spend on average four years in the asylum system.

Chief executive Enver Solomon said the document “fails to evaluate the true costs and consequences of the Bill”.

He added: “It does very little to predict the actual cost of implementing the Bill, and offers no estimates of the number of arrivals after the Bill becomes law. The Home Office admits in this assessment that it does not know how much of a deterrent effect the Bill will actually have, yet it still relies on this assumption to claim financial savings will be made.

“The assessment’s predictions of future costs if the Bill is not implemented assume no improvements to decision-making efficiency, accommodation costs, or broader system enhancements.

“The reality is that making quicker decisions remains the most effective way to reduce the cost of asylum accommodation.”

Shadow home secretary Yvette Cooper called the impact assessment a “complete joke”.

“By its own admission, this failing Conservative government is totally clueless on how much this Bill will cost or what the impact of any of its policies will be. They are taking the country for fools,” the Labour MP said.

“The few figures the Home Office has produced show how chaotic and unworkable their plans are.”

The document came as Ms Braverman’s plan to house asylum seekers on barges was branded “unworkable” as she missed her own target for the first vessel to be in place.

Migrant accommodation
The Bibby Stockholm accommodation barge is due into Portland, Dorset within ‘the coming weeks’, according to the Home Office (Matt Keeble/PA)

The Bibby Stockholm accommodation vessel, which will house around 500 people, is not yet in Portland Port, Dorset, despite Mrs Braverman promising MPs it would be in the dock a week ago.

The barge is currently in Falmouth, Cornwall, for checks, maintenance and refurbishment work.

On Monday June 5, the Home Secretary told the Commons “we will see an accommodation barge arrive in Portland within the next fortnight”.

Liberal Democrat home affairs spokesman Alistair Carmichael said: “This seems to be another case of Home Office policy by press release that is failing to materialise.

“Braverman’s plan for a barge on the Dorset coast is an unworkable plan that is wasting time and money, much like all of this Government’s asylum policy.”

The Home Secretary wants to use barges and sites including converted military bases to house asylum seekers and reduce the £6 million daily cost of hotel accommodation while people await a decision on their status.

The Bibby Stockholm was the first barge secured under the plan, but its journey to Portland will now take place in the coming weeks, according to the Home Office.