More than 800 people tried to cross the English Channel to the UK in boats, the largest number in one day.
Thirty boats crossed the waterway, one of the world’s busiest shipping lanes, to sail from France on the final leg of a journey to British shores.
The 828 migrants who landed on Saturday eclipsed the daily record of 592 set on August 12.
Bella Sankey, director for immigration charity Detention Action, said the Home Office “needs to confront reality”.
“Refugees will continue to come to the UK, as they have for centuries, as long as there are despots, wars and persecution in this world,” she said.
“To end the use of small boats, MPs should create a humanitarian visa system for people in France who are travelling to the UK so they can arrive here in safety and with dignity to make their claims.”
An Eritrean man aged 27 died this month as he and four others jumped overboard when their boat started to sink in the Channel.
“These dangerous crossings from safe EU countries are completely unnecessary, and we are determined to take down the evil criminal gangs behind them,” said Dan O’Mahoney, the UK’s Clandestine Channel Threat Commander who was appointed by the Home Office this month.
Migrants arrive in droves during summer months
“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 [at crossing], secured nearly 300 arrests and 65 prosecutions.”
French authorities prevented another 193 people in 10 boats from reaching Britain.
The UK government said it wants migrants to follow safe and legal routes to be admitted into the UK rather than risk the dangerous Channel route, but this year 12,500 people are known to have made the journey often in unseaworthy boats.
France has agreed to double police patrols on its beaches in a deal with Britain that will also improve the sharing of intelligence.
As the UK tries to close off the Channel route, where migrants are often in the hands of human traffickers, it is also dealing with the fallout of the Taliban takeover in Afghanistan.
Britain will allow 5,000 Afghans in as part of the humanitarian crisis and an additional 15,000 people will be allowed to travel to live in the UK as part of a longer-term plan.
The government has been criticised for the scale of its response and for putting in danger the lives of Afghans who worked with British military or diplomats.
Dozens of Afghan interpreters protested outside the Home Office on Monday, demanding that their extended families and former colleagues are helped to leave Afghanistan and saved from the Taliban.
Home Secretary Priti Patel has promised to make the Channel route "unviable" and proposed legislation to overhaul asylum rules, imposing stricter sentences for people smugglers and, controversially, migrants themselves.
She said the changes, which have been criticised by human rights groups, are long overdue.
Mr O'Mahoney said the plan "will fix the broken asylum system so it can no longer be exploited in this way".