Confusion surrounds the legal status of scores of people set to be deported to Jamaica.
The government has defended a flight set to deport 50 people to the Caribbean, saying it is "criminality not nationality which counts", despite concerns the Windrush scandal could be repeated.
Duncan Lewis Solicitors, which is representing 15 people due to be on the flight, filed papers at the High Court and called for an urgent oral hearing on Monday afternoon to discuss the matter.
But Home Secretary Priti Patel said she was legally obliged to order the deportation of foreign criminals who had received sentences of 12 months or more in prison.
Late on Monday, the Court of Appeal ordered the Home Office not to remove anyone scheduled to be deported from two detention centres near Heathrow Airport on the 6.30am flight to Jamaica on Tuesday - "unless satisfied (they) had access to a functioning, non-O2 Sim card on or before February 3".
Lady Justice Simler granted the order without a court hearing following an urgent application on paper by charity Detention Action.
The charity argued that some of the detainees at Colnbrooke and Harmondsworth detention centres still do not have a functioning mobile phone, following issues with an O2 phone mast in the area, and did not have adequate access to legal advice.
It was not clear to how many this could apply - and nor whether they would be on the plane or not.
A Home Office spokeswoman later said: "The planned charter flight to Jamaica is specifically for deporting foreign national offenders. Those detained for removal include people convicted of manslaughter, rape, violent crime and dealing Class-A drugs.
"We are urgently asking the judge to reconsider their ruling and it would be inappropriate to comment further whilst legal proceedings are ongoing."
Home Office minister Kevin Foster had earlier gone further in defending the planned flight, saying the flight is about "keeping the public safe".
He added: "It does not matter what part of the world they are from, whether it is the United States, Jamaica, Australia or Canada, it's criminality not nationality which counts."
Shadow home secretary Diane Abbott said many of the proposed deportees came to the UK as children and "have no memory of Jamaica", adding those on the flight were being punished twice.
"Does the Home Secretary accept that these deportations constitute double jeopardy because the persons have already served an appropriate sentence for their crime," she asked.
"And is the Home Secretary aware that over 170 MPs from all political parties have written to the Prime Minister calling for this deportation flight to be halted."
She urged the Government not to repeat the mistakes of the Windrush scandal.
A number of the people due on the flight are thought to have been convicted of drug offences when they were young.
One of those on the flight is a 23-year-old who came to the UK aged five and served half of a 15-month sentence in 2015 after being convicted of possessing class A drugs with intent to supply at 17.
Labour's David Lammy suggested the flight should be stopped at least until a report into the Windrush scandal had been published.
He said a leak of the report revealed its author Wendy Williams says the government "should not be deporting people under the age of 13".
He asked Mr Foster to confirm "that there are people on that flight who arrived in this country aged two, aged three, aged five, aged 11."
Members of the Windrush Generation came to the UK from Caribbean countries - many on the boat HMS Empire Windrush - and were given a legal right to work in the UK following World War II.
The Windrush scandal relates to those who were wrongly detained, denied legal rights, threatened with deportation and wrongly deported from the UK by the Home Office.
Tottenham MP Mr Lammy said the deportation flight shows the government "holds with such disrespect the contribution of West Indian, Caribbean and black people in this country".
He said: "When, when will black lives matter again?"
Mr Foster said the deportation was going ahead to protect the public and "cannot and should not be conflated with the wrongs suffered by the Windrush generation".
Toufique Hossain, director of public law at Duncan Lewis - who is leading the legal challenge, said many of the clients had come to the UK as young children aged between four and 13.
He said: "We are about to submit court papers to launch a judicial review and have asked for an urgent oral hearing in the High Court this afternoon."
Campaigners have said that their "information indicates that most have been convicted of drugs-related offences, often only once, and several have been groomed into county lines operations.
“These individuals are more British than foreign and their removal is neither reasonable nor proportionate."
He added: "And let's be clear, there are no British nationals on that flight. And let's be clear, the foreign nationals on that flight have been sentenced to a total of 300 years in prison.
"The offences are, as we said, relate to everything from sex offending, serious drug trafficking offences, violent offences, firearms offences - you know, that is what is happening in this instance."
The flight is thought to be leaving the UK at 6.30am on Tuesday.
However, more than 170 cross-party MPs have called on the Prime Minister to halt the flight amid concerns people who came to the country as young children will be on board.
It follows news of a leaked report commissioned by ministers in the wake of the Windrush scandal which warned the Government that the policy should be reconsidered in all but the "most severe cases".
Earlier on Monday, Cabinet Minister Rishi Sunak was asked about the case of Tajay Thompson who is facing deportation to Jamaica having served half of a 15-month sentence in 2015 after being convicted of possessing class A drugs with intent to supply at 17.
Mr Thompson, now 23 and living in south London, said he has no links to the Caribbean nation, which he has only visited twice since coming to the UK aged five.
“I feel like I was born here.
"Jamaica is not my country,” Mr Thompson said as he insisted he was groomed into a gang as a teenager.
“It’s not like I’m a rapist or a murderer, I’ve made a mistake when I was 17 and it’s now going to affect my whole life.”
Mr Sunak said he was not familiar with Mr Thompson’s case but insisted “all due process will have been followed”.
Labour MP Nadia Whittome organised the letter protesting against the Home Office flight which she says is intended to deport people who have been resident in the UK for decades.
“The fact is that many of the individuals in question have lived in the UK since they were children and at least 41 British children are now at risk of losing their fathers through this charter flight,” the Nottingham East MP said.
“The Government risks repeating the mistakes of the Windrush scandal unless it cancels this flight and others like it until the Windrush Lessons Learned Review has been published and its recommendations implemented.”
Labour shadow immigration minister Bell Ribeiro-Addy said the flight is “the most brutal and inhumane way to remove people from this country”.
“It often lacks due process, has little regard for deportees’ safety, and even less for their right to a family life,” she added.
A draft of a report commissioned by the Government in the wake of the Windrush scandal recommended that ministers rethink the flights, particularly for those who came to the UK as children.
The draft, written in June 2019 said: “Government should review its policy and approach to FNOs (foreign national offenders), if necessary through primary legislation.
“It should consider ending all deportations of FNOs where they arrived in the UK as children (say before age of 13). Alternatively – deportation should only be considered in the most severe cases.”
On Monday, the House of Commons will also hold a Second Reading debate on the Windrush Compensation Scheme (Expenditure) Bill, which would give the Government financial authority to make payments for people who suffered adverse effects as a result of not having the right documents to demonstrate their UK status.