Priti Patel defended her plan to send migrants to Rwanda after more than 1,000 crossed the Channel to the UK in a day for the second time in a fortnight.
Ministry of Defence (MoD) figures show 1,160 people were detected on Sunday in 25 boats, suggesting an average of around 46 people per boat.
This is the second time this year the daily total has topped 1,000, after August 22 saw a record 1,295 people intercepted in 27 boats.
The latest crossings, which mean the number for 2022 so far is edging closer to exceeding the tally for the whole of last year, come as campaigners challenged the Government’s agreement with the east African nation in court.
Meanwhile, the High Court case – in which several asylum seekers, the Public and Commercial Services union (PCS) and groups Care4Calais and Detention Action are questioning the legality of the plan – began.
Later on Monday, Ms Patel confirmed in a letter to Mr Johnson that she would step down as Home Secretary once Liz Truss takes office as prime minister and a successor is appointed.
In April, she signed what she described as a “world-first agreement” with Rwanda in a bid to deter migrants from crossing the Channel.
But the first deportation flight – due to take off on June 14 – was grounded amid a series of legal challenges.
Since the deal was announced, 22,116 people have crossed the Channel to the UK in small boats.
Former Labour leader Jeremy Corbyn was among those to address dozens of protesters who gathered outside the Royal Courts of Justice and chanted “say it loud, say it clear, refugees are welcome here” while waving placards saying “Stop Rwanda” as the case continued inside.
During the hearing those disputing the policy said Rwanda was an “authoritarian state” that “tortures and murders those it considers to be its opponents”.
But later in the Commons Ms Patel stood by her move, replying “absolutely not” when she was asked to abandon the policy and insisting it was “legitimate”.
At the same time the Home Office posted a video online of Ms Patel describing Rwanda as an “incredible country that has a very, very progressive and developed approach in terms of, not just how they treat people, but effectively how they are governed”.
And in a written ministerial statement outlining the work of the Home Office since April this year, the Home Secretary said the agreement “fully complies with all national and international law and we prepare for delivery.”
More than 27,300 people have crossed the Channel from France to the UK in small boats, such as dinghies, so far in 2022. This is just over 1,000 short of the number of arrivals for the whole of last year (28,526).
Included in Sunday’s total were 29 people found by police and immigration officers after landing on Folkestone’s west beach at around 11.45am when one boat made it to the coast unaccompanied.
Video footage circulating online appeared to show a boat full of people arriving on the south coast before some of the group started to run up the beach.
Those found were taken to Dover to be processed and officers “continue to make enquiries to locate any potential absconders”, the MoD said.
It is unclear whether anyone else remains unaccounted for and the Home Office said it would not comment on a live investigation.
This is the second time this year an “uncontrolled landing” has been recorded by the MoD, with the first reported on June 2. 2021 saw 39 uncontrolled landings, with 32 by this point in the year, the MoD said.