Nearly 1,000 migrants arrived in the UK yesterday after crossing the Channel, government figures show.
Long lines of people - believed to be migrants - could be seen waiting to be processed at the Border Force compound in Dover, Kent, as 990 arrived on British shores.
Saturday's figure is the biggest number of arrivals in a single day for many weeks.
The highest number in a single day was set on 22 August when 1,295 people arrived in the country.
Nearly 40,000 have arrived in the UK so far this year after attempting the treacherous trip from France.
They have crossed the world's busiest shipping route in dinghies and other small boats, provisional figures show.
Unseasonably warm weather has seen the kind of settled conditions that encourages crossings.
Processing centre 'past the point' of being safe
It comes after an immigration watchdog said he was left "speechless" by conditions at the Manston migrant processing centre in Kent.
David Neal, the chief inspector of borders and immigration, said the centre was "past the point" that it can be safe and run properly and accused the Home Office of a "creeping lack of ambition".
Manston was originally meant to hold between 1,000 and 1,600 people, but there were 2,800 at the site when Mr Neal visited on Monday.
Migrants are meant to stay at the short-term holding facility, which opened in January, for 24 hours while they undergo checks before being moved into immigration detention centres or asylum accommodation - currently hotels.
The Sunday Times reported Home Secretary Suella Braverman has been accused of failing to act on legal advice received at least three weeks ago which warned migrants were being detained for unlawfully long periods.
A Home Office spokesperson said these claims were "completely baseless".
It added: "The Home Secretary has taken urgent decisions to alleviate issues at Manston and source alternative accommodation. Claims advice was deliberately ignored are completely baseless.
"It is right we look at all available options so decisions can be made based on the latest operational and legal advice.
"The number of people arriving in the UK via small boats has reached record levels, which has put our asylum system under incredible pressure and costs the British taxpayer millions of pounds a day."
Cabinet minister Michael Gove said the situation at Manston is "deeply concerning", but he denied the home secretary ignored or dismissed legal advice.
"The situation in Manston is not what it should be," he told Sky News's Sophy Ridge On Sunday programme.
"Everyone acknowledges that. We have more than 2,000 people there at the moment."
The Liberal Democrats have called on the government to publish the legal advice reportedly ignored by Ms Braverman.