LONDON — Britain and France signed a new agreement on Monday to stem the growing number of small boats carrying migrants over the busy waterway between them, a sign of thawing relations on an issue that has become a sore point for the embattled British government.
Under the agreement, Britain will pay France some 72.2 million euros ($74.5 million) over 2022 and 2023 — a previous deal involved a €62.7 million contribution — and in turn, France will increase security patrols on its northern beaches by 40 percent, the countries said in a joint statement.
The arrival of small boats on British shores has become a focus of discontent among supporters of Britain’s governing Conservatives, even as the party has endured a tumultuous year that has seen three prime ministers in a matter of months. The issue has also been at the center of contentious diplomacy between Britain and France, close allies and historic rivals whose relationship is being reshaped by Britain’s departure from the European Union.
The crossings stoked tensions between Boris Johnson, the former British prime minister, and President Emmanuel Macron of France. Liz Truss, who briefly succeeded Mr. Johnson in September, also appeared willing to take a provocative stance, answering “the jury’s out” when asked during her leadership campaign whether Mr. Macron was a friend or a foe.
Prime Minister Rishi Sunak, who succeeded Ms. Truss last month, seems to be taking a softer approach. Speaking with reporters on his way to the Group of 20 summit, the BBC said, Mr. Sunak praised Monday’s agreement and said that he had “spent more time working on that than anything else” since he took office.
Britain’s Ministry of Defense said that 853 people had arrived in Britain by small boat on Sunday alone, bringing the total number of such arrivals this year to more than 40,000.
Though Britain’s asylum system has been slow to assess claims, the vast majority of small-boat arrivals whose cases have been examined have been found to be refugees from war or persecution. Rights groups have criticized the use of heated rhetoric around the crossings, which make up a fraction of the number of people arriving in the country.
In a joint statement, the two governments said that the agreement had been signed “with a view to making the small boat route unviable,” as well as to “save lives, dismantle organized crime groups and prevent and deter illegal migration in transit countries and further upstream.”
Suella Braverman, the British cabinet minister responsible for security and immigration, said the small boat crossings were “a global challenge requiring global solutions” and added that it was “in the interests of both the U.K. and French governments to work together to solve this complex problem.”
More on the Political Situation in Britain
“We must do everything we can to stop people making these dangerous journeys and crack down on the criminal gangs,” she said in a statement.
The two governments also agreed to create a task force “focused on reversing the recent rise in Albanian nationals and organized crime groups exploiting illegal migration routes into Western Europe and the U.K.”
Separate British and French inquiries into the wreck continue. But on Sunday, the French newspaper Le Monde reported in a damning investigation that while the French Coast Guard took repeated distress calls from people on the boat on the night of the accident, including cellphone messages that identified the sinking vessel’s location, it ignored their pleas for help and instead waited for the boat to reach British waters.
The investigation was based on unreleased transcripts of distress calls and police interviews of coast guard officers, and described the French maritime authorities as understaffed and overwhelmed by repeated nightly crossings.
The French Coast Guard did not send any emergency vessels, Le Monde reported. Instead, it contacted its British counterparts to inform them that the boat was approaching British waters and waited for it to leave French jurisdiction, assuring the desperate migrants all the while that help was on the way, Le Monde said.
People on the boat continued to call more than a dozen times, with crying men, women and children heard in the background, the newspaper said. When one of them said that they were “in the water,” one coast guard officer answered, “Yes, but you are in English waters,” the newspaper said.
The Paris prosecutor’s office, which is handling the investigation, and French maritime authorities did not immediately respond to a request for comment on Le Monde’s report. A local maritime official told Le Monde, “We have not had any feedback from the investigation to make the link between the exchanges that night and the wrecked boat.”
Mr. Macron’s government is expected to present an immigration bill in January that would toughen parts of the process for migrants seeking asylum in France and make it easier for the authorities to deport immigrants who are in France illegally, but that would also make it easier for longtime undocumented workers to get papers and for employers in sectors with labor shortages to hire immigrants.
Megan Specia reported from London, and Aurelien Breeden from Paris.