The government will face two court challenges on Monday in response to its immigration policy of sending some asylum seekers to Rwanda.
A High Court judge ruled on Friday that the first flight to the East African country could go ahead on Tuesday but this is set to be challenged in the Court of Appeal.
The appeal has been lodged by the Public and Commercial Services union, which represents more than 80 per cent of Border Force staff, along with the Care4Calais and Detention Action charities.
A second case is due to be heard in the High Court on Monday after Asylum Aid, a refugee charity, applied for an urgent interim injunction to stop the government flying migrants to Rwanda.
Mr Justice Jonathan Swift, who ruled on the first case on Friday, is also set to hear the second case.
Rwanda’s high commissioner Johnston Busingye told The Telegraph that the country will be a “safe haven” for migrants, after The Times and the Daily Mail reported that the Prince of Wales said in private that the policy was “appalling”.
“Disappointingly, much of the discussion has either questioned our motives for entering the partnership or doubted our ability to provide safe haven to those in need — as was the case in Friday’s legal proceedings,” Mr Busingye wrote in the paper.
“There’s no doubt that we are a work in progress, every country is, but the Rwanda of today is unrecognisable from the country the world was introduced to in 1994."
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British Home Secretary Priti Patel said the “vast majority” of those who arrived in the UK through means considered to be “illegal”, such as on unauthorised boats or stowed away in lorries, would be considered for relocation.
It is understood that adults will be prioritised for relocation under the scheme, with officials insisting families arriving in the UK will not be split up.
On Sunday, PCS general secretary Mark Serwotka said the union hoped it could win its appeal and stop the first deportation flight.
“We hope we win tomorrow in the Court of Appeal to stop the flight [on Tuesday]," he told Sky. “But of course, the legality of these proposals will only be tested out at the full court hearing in July.
“We’re absolutely confident that in July, in line with what the UNHCR said very graphically in court, we believe these proposals will be found to be unlawful.”
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As of Friday, up to 130 people had been notified they could be removed.
On Friday, the High Court in London heard 31 people were due on the first flight, with the Home Office planning to schedule more this year.
But The Telegraph reported fewer than 10 people were now expected on the first flight.
The first claim against the policy was brought by lawyers on behalf of some asylum seekers alongside PCS, as well as Care4Calais and Detention Action, who are challenging the policy on behalf of everyone affected.
But Mr Swift ruled against granting a temporary block to the policy until a full hearing next month.
“I do not consider that the balance of convivence favours the grant of the generic relief,” he said.
Shortly after his ruling at the High Court, Mr Swift granted the claimants permission to appeal.