Five asylum seekers facing deportation to Rwanda are victims of trafficking and torture, according to a charity.
Clare Moseley, the founder of Care4Calais, revealed the personal circumstances of the seven migrants removed from a plane set to take off at 10.30pm last night.
The flight, set to cost hundreds of thousands of pounds, was halted after last minute interventions by the European Court of Human Rights (ECHR).
The Court confirmed it had granted an urgent interim measure in regards to an Iraqi national, and it was understood to be considering a number of further requests.
Explaining the difference between asylum seekers' personal cases and her charity's legal challenge, Ms Moseley told LBC: "Each of the individual people has their own lawyer, which is challenging in respect of their own personal circumstances.
"So that's what's led to people coming off the flight is each one of them has personally made a challenge on their own circumstances.
"So some of them were, for example, victims of torture and had really bad mental and physical scars from that. Some of them had been victims of trafficking, some had very bad mental health concerns, so one man for example had PTSD.
"So it's where their own personal, individual circumstances meant that they could not be deported as opposed to our challenge which is about whether or not the policy itself is lawful.
"Out of the seven people that we ended up with, five of them had been victims of trafficking and torture, and one of them had quite severe PTSD. So you can understand there were quite serious things going on there.
"Some of them are really struggling just with being in detention."
Out of the 130 asylum seekers selected for deportation to Rwanda, the "vast majority" arrived in the UK by boat while "16 or 17" crossed by lorry, said the charity boss.
She continued: "One of the issues was the government had been taking people straight off the boats as they arrived to a detention centre and then issuing them with this notice.
"But the problem is when you've just arrived in a foreign country and you don't speak the language and you don't know anybody and you don't have access to the internet, getting a lawyer and sorting our your claim and defence in a very short amount of time is very difficult."
Her comments came as Priti Patel described the ECHR's intervention as "very surprising", adding that "many of those removed from this flight will be placed on the next".
She said the Home Office legal team is reviewing "every decision made on this flight", and that preparation for the next flight "begins now".
Following the grounding of the flight on Tuesday night, the Home Secretary said: "I have always said this policy will not be easy to deliver and am disappointed that legal challenge and last-minute claims have meant today's flight was unable to depart.
"It is very surprising that the European Court of Human Rights has intervened despite repeated earlier success in our domestic courts.
"These repeated legal barriers are similar to those we experience with other removals flights and many of those removed from this flight will be placed on the next.
"We will not be deterred from doing the right thing and delivering our plans to control our nation's borders. Our legal team are reviewing every decision made on this flight and preparation for the next flight begins now."
Boris Johnson acknowledged there had been criticism of the plan from "some slightly unexpected quarters" but highlighted the legal profession as the main source of opposition to the Rwanda policy, which will send asylum seekers on a one-way trip to the African nation.
Refugee Council chief executive Enver Solomon said: "Whilst we are relieved to hear the flight to Rwanda did not take off as planned tonight, it is clear that the Government remain determined to press on with this deal - leaving us to continue to witness the human suffering, distress, and chaos the threat of removal will cause with far reaching consequences for desperate people who are simply in need of safety.
"The fact that the final flight could not take off is indicative of the inhumanity of the plan and the Government's complete refusal to see the face behind the case."
Mark Serwotka, general secretary of the Public and Commercial Services union, said: "We're pleased the courts have ruled to stop this flight.
"It's time for the Government to stop this inhumane policy which is the basest of gesture politics and start to engage seriously with sorting out the asylum system so those who come to our country seeking refuge are treated fairly and according to the law."
