Nearly 900 migrants crossed the English Channel in small boats on Saturday, the highest number on a single day so far this year.
On Saturday 872 people crossed the English Channel on 15 small vessels, according to the latest provisional government data.
That is an average of about 58 people per boat, and sends the total for the year to 20,973, putting the UK on course for a forecast 40,000 arrivals.
The spike comes despite UK Prime Minister Rishi Sunak’s vow to stop the soaring numbers of people making the treacherous voyage and after France increased security around the Calais coast.
Parliament returns on Monday with time running out for Mr Sunak to meet his pledge before a general election in 2024.
Ministers are battling in the courts to get their Rwanda deportation plan up and running, while hoping that tough new asylum laws will deter people from coming.
The Home Office said: “The unacceptable number of people risking their lives by making these dangerous crossings is placing an unprecedented strain on our asylum system.
“The government is going even further through our Illegal Migration Act which will mean that people arriving in the UK illegally are detained and promptly removed to their country of origin or a safe third country.”
In August, official figures showed that more than 100,000 migrants had crossed the Channel on small boats from France to south-east England since Britain began publicly recording arrivals in 2018, when only a handful made the trip.
The route across one of the world's busiest shipping lanes has repeatedly proved perilous, with numerous boats capsizing and scores of migrants drowning in the waters over the past decade.
In France increased security measures and more patrols have been introduced.
A chain of buoys now blocks a river, the latest measure deployed to try to stop Britain-bound migrants from crossing the Channel.
A plane belonging to Frontex, the EU border agency, and equipped with infrared and thermal cameras also tries to track down migrants.
About 800 security force personnel survey the beaches and dunes, but people still set sail.
The previous daily high for 2023 was 756 on August 10.
The total for the year so far is still lower than this time last year, when 25,000 people had already made the journey.
The record high for a single day since current records began in 2018 is 1,295 on August 22, 2022.
Saturday's arrivals mean 1,172 people have made the journey so far this week with crossings recorded on just two out of six days, after 300 migrants arrived on Tuesday.
Figures will be published on Monday for any crossings that took place on Sunday.
Total arrivals last year were 45,774, compared with the previously documented 45,755, according to the latest available Home Office data.
The average number of migrants crossing the Channel per boat hit a new monthly high in August, when some 5,369 people made the journey using 102 boats – an average of around 53 migrants per vessel.