The Home Office is facing legal action over conditions at the Manston migrant processing centre - as reports suggest asylum seekers were removed from the site and "abandoned" at London Victoria station.
Immigration minister Robert Jenrick told Sky News that a judicial review is being brought following reports of severe overcrowding at the centre in Kent.
Although Manston is meant to hold 1,600 people, estimates suggested 4,000 were being housed at the facility earlier this week.
Hundreds of people have been removed from the site in recent days, with Mr Jenrick expressing hope that Manston will return to being "legally compliant" soon.
In other developments, council chiefs in Kent have warned the county is at "breaking point" as a result of the migrant situation, with the potential for disorder at Manston and the risk of far-right violence.
They have written to the home secretary - urging her to stop using the county as an "easy fix" - and have warned they are under "disproportionate pressure" because of Kent's location.
There are no more school spaces for local children in Year 7 and Year 9 due to the unplanned arrival of young refugees, they said.
'Stressed, disturbed and completely disoriented'
Reports suggest a group of 11 asylum seekers were left at London Victoria without accommodation after being driven there from Kent on Tuesday.
The Under One Sky homelessness charity told The Guardian that many of them were in flip-flops and without winter clothes.
Volunteer Danial Abbas said: "They were stressed, disturbed and completely disoriented. They were also very hungry."
A British Transport Police spokesperson told the newspaper: "Officers engaged and liaised with charity partners, rail staff and government colleagues to help them find accommodation for the evening."
The government is facing criticism over this incident - with Liberal Democrat MP Alistair Carmichael raising it in the House of Commons yesterday.
He said Home Secretary Suella Braverman had refused to prematurely release people into local communities without them having anywhere to stay - but claimed this is "exactly what happened" on Tuesday.
"She has something to answer. It would be very useful for the House to know whether or not she intends to come here and explain herself or whether yet again she has to be brought," Mr Carmichael warned.
What judicial review means
Speaking to The Take with Sophy Ridge last night, Mr Jenrick said: "I believe we have received the initial contact for a judicial review.
"That's not unusual, this is a highly litigious area of policy but of course, as the minister responsible, I want to make sure everything we do is conducted appropriately and within the law."
Mr Jenrick said he could not reveal who had brought the judicial review as it was legally sensitive - but Sky News understands the Home Office has received the pre-action protocol letter and the department will be responding "in due course".
Judicial reviews determine the lawfulness of a decision or action made by a public body, in this case the Home Office. It takes about three to five months to get a decision, but an injunction can halt action immediately.
Work to make Manston 'humane and compassionate'
Mr Jenrick who was only appointed as immigration minister last week by Rishi Sunak, said he has been working with Ms Braverman to reduce the number of people at Manston - and the length of time they stay there.
While migrants are not meant to remain at the processing centre for more than 24 hours, some have been detained for much longer.
He added: "So the week I've been in post I've tried to work night and day to ensure the Manston site is not just legally compliant but is a humane and compassionate place where we welcome those migrants, treat them appropriately and then they leave quickly to alternative accommodation.
"The numbers at Manston have fallen very substantially since the weekend when we became aware of the specific issues and got involved so directly.
"I think we're on a path now where within a matter of days, assuming we don't see very large numbers of migrants coming across the Channel - I don't think that's going to happen as we have good forecasts of the weather and other intelligence from northern France."
Mr Jenrick denied he had taken over from Ms Braverman in handling this matter after she was accused of failing to listen to legal advice that said migrants from Manston needed to be sent to hotels after being processed within a day of arriving.
Meanwhile, Albania's prime minister has hit out at the UK government for blaming Albanians for the migration crisis.
'This is the Conservatives' making'
Labour's shadow home secretary Yvette Cooper said: "The Conservative government has no excuse. They have been warned about these problems for months and failed to act.
"These problems are entirely of their making - their decision-making has collapsed, so the backlog has grown and they clearly haven't planned or properly followed legal advice.
"We need urgent answers on what the home secretary knew and when. The prime minister promised integrity and professionalism but all they have shown is the opposite. This is complete chaos and they need to urgently get a grip."
A Home Office spokeswoman told Sky News: "The number of people arriving in the UK via small boats has reached record levels and continues to put our asylum system under incredible pressure.
"Manston remains resourced and equipped to process migrants securely and we will provide alternative accommodation as soon as possible.
"We urge anyone who is thinking about leaving a safe country and risk their lives at the hands of criminal people smugglers to seriously reconsider. Despite what they have been told, they will not be allowed to start a new life here."