Asylum seekers who have made the Channel crossing can be detained for up to four days under new rules quietly announced by the Government.
The Tories have handed themselves the power to quadruple the length of time that migrants can be held in short-term processing facilities like crisis-hit Manston, in Kent, from January 5.
Home Secretary Suella Braverman is tweaking the law so people who have arrived in the UK in small boats can be held for "a period of not more than 96 hours" - unless a longer period is authorised by the Government.
Under previous rules, asylum seekers could only be detained for up to 24 hours.
The Government came under intense pressure over major overcrowding at Manston in the autum n, when it emerged that some migrants were being detained beyond the 24-hour legal limit.
At one point the facility held as many as 4,000 people despite being designed to hold just 1,600 detainees.
It is only designed to house people for short periods for security and identity checks before they are moved to longer term accommodation
The Home Office admitted last month that the death of a man held at the centre may have been caused by diphtheria, despite downplaying reports of outbreaks of disease in the facility.
Rishi Sunak has made tackling the small boats crisis one of his top priorities, and this week unveiled a hardline crackdown, including removing Albanian arrivals and housing asylum seekers in "disused holiday parks, former student halls and surplus military sites".
Ms Braverman said she "won't stop until we have seen progress" after four migrants died and more than 40 were rescued as a boat capsized in the Channel in sub-zero temperatures.
Official figures from the Ministry of Defence revealed that 401 migrants crossed the Channel on Wednesda - the day four people died after a boat capsized.
The latest figures take the provisional total for the number of migrants who have made the crossing so far this year to 45,223, PA analysis of Government data shows.
