By Michael Holden and Sam Tobin
LONDON (Reuters) -Britain's plan to deport migrants to Rwanda reached the UK's top court on Monday, as the government argued there was a need to deter Channel crossings while asylum seekers and the United Nations' refugee agency said Rwanda was unsafe.
Government lawyers asked the Supreme Court to overturn a ruling by a lower court in June that the scheme to send thousands of asylum seekers more than 4,000 miles (6,400 km) to East Africa was unlawful, as Rwanda was not a safe third country.
Under recent legislation, the vast majority of those who arrive in Britain by small boat across the Channel from France would have their asylum claims made inadmissible and be subject to deportation.
London's Court of Appeal had ruled those sent to Rwanda would be at risk of being sent home where they could face persecution, making the policy unlawful under Britain's Human Rights Act, which made the European Convention on Human Rights (ECHR) part of British law.
That decision dealt a massive blow to Prime Minister Rishi Sunak's pledge to stop thousands of migrants from arriving in small boats on the English south coast.
On Monday, the government's lawyer James Eadie told the UK's top court there was "a serious and pressing need to take effective steps that will act as a deterrent to those undertaking the perilous and sometimes life-threatening journey" across the Channel.
Raza Husain, a lawyer representing eight of the asylum seekers involved in the case, countered that people sent to Rwanda were at risk of being returned to their home countries in breach of international law.
He said Rwanda was "an authoritarian, one-party state" and that its regime "repeatedly imprisons, tortures and murders those it considers to be its opponents".
The UN High Commissioner for Refugees (UNCHR) has intervened in the appeal to argue it is not safe to send asylum seekers to Rwanda.
The agency "maintains its unequivocal warning against the transfer of asylum seekers to Rwanda", its lawyers said in court filings.
Legal teams representing migrants from Syria, Iraq, Iran, Vietnam and Sudan also want the court to conclude the scheme is unlawful because asylum seekers face inhuman or degrading treatment within Rwanda.
The Rwandan government has said it will offer migrants deported from Britain the opportunity to build a new, safe life.
HIGH STAKES
The political stakes are high and the outcome, with a final ruling likely by year-end, could have far-reaching consequences.
Sunak, whose Conservatives are trailing by about 20 points in opinion polls ahead of an election expected next year, has made a vow to "stop the boats" one of his five priorities as he seeks to turn around his party's fortunes.
Surveys show that immigration, a key factor in the 2016 referendum vote for Britain to leave the European Union, remains a major concern for voters, and that a majority of the public think the government is handling the issue badly.
The government's first planned Rwanda deportation flight had been due to leave in June last year, but was blocked at the last minute by an injunction from the European Court of Human Rights until all the UK legal action had been concluded.
Some in Sunak's party want Britain to pull out of the ECHR to prevent any repeat.
"Know this; I will do whatever is necessary to stop the boats," Sunak told the Conservative conference.
The court case comes as governments around the world wrestle with how to cope with the arrival of hundreds of thousands of migrants fleeing war zones or seeking better lives in the West.
In the United States, President Joe Biden's administration said it would add sections to a border wall to stave off record crossings from Mexico, while in Europe, governments are grappling with how to cope with the arrival of hundreds of thousands of migrants from Africa, Asia and the Middle East.
(Reporting by Michael Holden and Sam Tobin; editing by Mark Heinrich, Christina Fincher and Toby Chopra)