London, Nov 15 (IANS): In a big setback to Prime Minister Rishi Sunak's government, the UK's Supreme Court on Wednesday rejected plans to send migrants to Rwanda as unlawful as it would put them at risk.

Issuing a unanimous judgement, the country's highest court said that the policy would put asylum seekers at “risk of ill-treatment” as they could be sent back to their home countries once they land in Rwanda.

Sunak, who has vowed to stop migrants reaching Britain in small boats across the English Channel, said the ruling "was not the outcome we wanted".

"We have seen today’s judgment and will now consider next steps. This was not the outcome we wanted, but we have spent the last few months planning for all eventualities and we remain completely committed to stopping the boats," he said in a statement.

The Prime Minister, however said that his "commitment to stopping the boats is unwavering".

"The Government has been working on a new treaty with Rwanda, and we’ll finalise that in light of today’s judgment. If necessary, I am prepared to revisit our domestic legal frameworks," Sunak wrote on X on Wednesday.

The development comes just after sacked Home Secretary Suella Braverman, in a searing letter, accused Sunak of betraying his pledge to do "whatever it takes" to stop small boats crossing the Channel.

Braverman said that the PM had no “Plan B" if the government lost the Supreme Court case.

Since Brexit, net immigration has continued to mount, touching a record of 606,000 in 2022.

Last year, a record 45,775 people were detected arriving without permission in Britain in small boats. So far this year, more than 27,000 have arrived this way.

Launched in April 2022 by then Prime Minister Boris Johnson, the Rwanda plan aims to discourage asylum seekers from making the perilous journey of about 20 miles across the Channel from Europe in small boats or inflatable dinghies to England's southern beaches.

Under the plan, anyone who arrived in Britain illegally after January 1 last year faced deportation to Rwanda.

Following a last minute injunction from the European Court of Human Rights, the first deportation flight in June 2022 was blocked.

According to media reports, UK is presently spending over three billion pounds per year on dealing with asylum applications, and the cost of housing migrants as their claims are processed runs at about 6 million pounds per day.