Over 700 migrants in small boats crossed the Channel to Britain on Sunday, the highest number on a single day since Prime Minister Keir Starmer took power vowing to tackle people-smugglers.
Two migrants who attempted the crossing died, French authorities said earlier, taking the number of people to lose their life on the dangerous sea journey to 25 since the start of the year.
Some 703 people arrived on Sunday on 11 boats, according to provisional interior ministry figures released on Monday.
Stopping the small boat arrivals was a key issue in Britain's general election in July.
Within days of taking power, Starmer scrapped a controversial scheme to deport migrants to Rwanda.
The plan was a flagship policy of the last Conservative government.
Starmer has instead pledged to dismantle the people-smuggling gangs who organise the crossings and are paid thousands of euros by each migrant.
The latest figures come after the UK has been rocked by anti-migrant unrest, following a knife attack on July 29 that killed three children and was falsely linked on social media to a Muslim immigrant.
Thousands of anti-racism demonstrators rallied across Britain on Saturday against riots that targeted mosques and hotels linked to immigration.
Starmer and France's President Emmanuel Macron have pledged to strengthen "cooperation" in handling the surge in undocumented migrant numbers.
The latest crossings take the number to make the journey since the start of 2024 to 18,342, 13 percent higher than at the same time last year.