The UK government’s controversial plan to send asylum-seekers to Rwanda is has been blocked by an appeal court in what is a blow to the Conservative government’s vow to stop migrants crossing the English Channel in boats.

The ruling by the UK’s Court of Appeal found that Rwanda could not be considered a “safe third country” where migrants from any country could be sent.

It came after revelations that sending an asylum seeker to Rwanda would cost 169,000 pounds (or $A322,000) – more than it would cost to house the person in the UK. The amount includes a 100,000 pound payment to Rwanda.

The Appeal Court judges said that a policy of deporting asylum seekers to another country deemed safe was not in itself illegal, and the government said it would challenge the ruling in UK’s High Court. It has until July 6 to lodge an appeal.

UK Prime Minister Rishi Sunak said that “while I respect the court I fundamentally disagree with their conclusions.”

Mr Sunak has pledged to “stop the boats” – a reference to the overcrowded dinghies and other small craft that make the journey from northern France carrying migrants who hope to live in the UK.

More than 45,000 people arrived in Britain across the Channel in 2022, and several died in the attempt.

The UK and Rwanda struck a deal a year ago that would see some migrants who arrive in the UK as stowaways or in small boats would be sent to the African nation, where their asylum claims would be processed.

Those granted asylum would stay in Rwanda rather than return to Britain.

The U.K. government argues that the policy will smash the business model of criminal gangs that ferry migrants on hazardous journeys across one of the world’s busiest shipping lanes.

The UK’s Home Secretary Suella Braverman, who has launched a hard-line and vocal campaign against migrant arrivals, said the ruling would encourage the flow of irregular migrants.

But human rights groups point to rights abuses and repression in Rwanda, which is ruled by effective dictator Paul Kigame.

Lawyers representing asylum seekers told the court it was immoral and inhumane to send people more than 6,400 kilometres to a country they don’t want to live in, while arguing that most Channel migrants are desperate people who have no authorised way to come to the U.K.

They also cited Rwanda’s poor human rights record, including allegations of torture and killings of government opponents.

Human Rights Watch UK welcomed the verdict and urged the government to “abandon this unworkable and unethical fever dream of a policy and focus her efforts on fixing our broken and neglected migration system”.

Britain’s High Court ruled in December that the policy is legal and doesn’t breach Britain’s obligations under the UN Refugee Convention or other international agreements.

But the court allowed a group of claimants, who include asylum-seekers from Iraq, Iran and Syria facing deportation under the government plan, to challenge that decision on issues including whether the plan is “systemically unfair” and whether asylum-seekers would be safe in Rwanda.

More than 45,000 migrants arrived on the shores of southeast England on small boats in 2022 – a 60-percent annual increase on a perilous route that has been used by more people every year since 2018.