A key parliamentary committee says the government's plan to send some asylum seekers to Rwanda is fundamentally incompatible with the UK's human rights safeguards.
The Joint Committee on Human Rights says the legislation jeopardised the UK's international reputation.
The bill will be debated in detail by the House of Lords this week and face substantial opposition.
The UK Supreme Court ruled that Rwanda was not a safe country because it could send victims of abuses, including torture, back to countries they have fled from.