Suella Braverman has widened the scope of the agreement since it was ruled lawful by the High Court in December, meaning that it can also be applied to modern slavery victims and other small boat migrants.
The Asylum Aid charity will argue that selected people are not being given sufficient opportunity to challenge the decision, or the proper time, information and access to legal advice.
Chief executive Kerry Smith said: “The High Court’s decision – that people do not require legal advice, that they should be able to understand the process and make representations within seven days, and that they have no right to make representations on the government’s position that Rwanda is safe – risks denying all those subjected to this procedure a fair hearing.
“The lack of safe routes for those fleeing persecution and violence means that, together with the Illegal Migration Bill, the shortcut Rwanda processing policy will ensure that survivors of torture, trafficking and other forms of human cruelty are blocked from the systems that enable them to secure safety.”
Freedom From Torture, which is intervening in the case, said it “cuts to the heart of the UK’s role as a place of safety for survivors of torture and persecution”.
“In this exceptionally hostile and fast-paced scheme, there is a grave risk that torture survivors will not be identified and will be expelled from the UK,” warned chief executive Sonya Sceats.
“No matter what the courts decide, this scheme and the ‘refugee ban bill’ are unacceptable and contrary to the compassion we should be showing to people who need our help.”
The arguments will be considered at a four-day hearing, starting on Monday, and judges are expected to reserve their decision to a later date.
Ministers have said flights to Kigali will not be attempted until the case is decided, and whichever side loses at the Court of Appeal could take it to the Supreme Court.
The latest stage of the Rwanda legal challenge coincides with the return of the controversial Illegal Migration Bill to parliament.
It aims to allow the UK to detain and deport small boat migrants without considering their asylum claims and, with no other return agreements in place, the Rwanda deal is crucial to its success.
A slew of amendments, both hardening and softening aspects of the proposed laws, will be considered by MPs on Tuesday before the bill passes to the House of Lords.
Analysis conducted by the Refugee Council and Barnardo’s estimated that if the bill passes as currently drafted, almost 15,000 unaccompanied child asylum seekers would be locked up and banned from remaining in the UK when they turn 18 in the first three years of the law being in place.
The charities said most child asylum seekers come from countries with high grant rates for refugee status, like Afghanistan, and are “forced to take dangerous journeys because there are very limited options for safe routes to the UK”.
Refugee Council chief executive Enver Solomon said: “The idea of locking up children separated from their families and then kicking them out of the country when they turn 18 is deeply disturbing to most people in the UK. This is not who we are as a country.”
Lynn Perry MBE, the chief executive of Barnardo’s, said the bill has “serious implications for the safety and protection of children”.
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