Ministers faced pressure to axe plans to lock up unaccompanied children who arrive on small boats for longer.
The limit now is 24 hours for the unaccompanied.
More than 150 groups and faith leaders urged Prime Minister Rishi Sunak to scrap the “extreme and cruel” plan.
The British Medical Association, which has ground the NHS to a halt through strikes, is among vocal critics.
The NSPCC, Detention Action and Care4Calais, which launched the legal proceedings to stop Rwanda deportations, also signed a protest letter.
The Home Office said it has amended the Illegal Migration Bill so any “unaccompanied child could only be [deported] in very limited circumstances”, with detention periods lasting the “shortest possible time”.
Ministers believe ruling out detaining young people would merely lead people-smugglers to cram more into dinghies.
