A record 828 migrants were intercepted by the UK while crossing the English Channel on Saturday, the Home Office says.
The previous record for a single day was 592 on 12 August.
The UK was involved in 30 crossing events – including rescues – on Saturday, according to the Home Office, although none have since been recorded on Sunday or Monday.
French authorities stopped another 193 people crossing on Saturday in 10 different incidents.
In the whole of 2020, some 8,417 people arrived on the UK’s shores.
Dan O’Mahoney, the clandestine Channel threat commander for the UK government, said: “These dangerous crossings from safe EU countries are completely unnecessary and we are determined to take down the evil criminal gangs behind them.
“We’re working across government as well as with French and international partners to tackle this issue. We have doubled the number of police officers on French beaches, prevented more than 10,000 attempts, secured nearly 300 arrests and 65 prosecutions.
“The government’s new plan for immigration will fix the broken asylum system so it can no longer be exploited in this way.”
Home Secretary Priti Patel has vowed to make the Channel route “unviable”.
The Home Office under Ms Patel wants to increase prison sentences for those who try and enter the UK illegally to four years, and those who “facilitate” crossings to get a life sentence.
It also is encouraging people to claim asylum in the first “safe country” they reach, instead of making the dangerous crossing to the UK.
Charities have criticised Ms Patel and her department and called for more safe and legal routes for people wanting to claim asylum in the UK.
Lisa Doyle, director of advocacy and engagement at the Refugee Council, said: “The government needs to recognise that while there is war, persecution and violence, people will be forced to take dangerous journeys to seek safety.
“We are talking about ordinary men, women and children who are forced to flee their home through no fault of their own. The odds are stacked against them but they struggle on to survive.
“The government must change its approach. Instead of seeking to punish or push away people seeking safety because of the type of journey they have made to the UK, they must create and commit to safe routes.
“As a country, we can save lives and empower people, who have already been through so much, to give back to the communities that welcome them.”