LONDON — The number of migrants arriving in Britain in small boats crossing the English Channel rose more than sixfold over the past year, according to estimates from the BBC and other news organizations, even as the government moved to step up enforcement.

At least 1,892 people arrived by small boats crossing the Channel in 2019, according to research by the BBC. That remains a small fraction of the number crossing the Mediterranean to continental Europe — more than 100,000 last year, according to the United Nations, down from more than a million in 2015.

But it contrasts with the government’s official figure of 297 for Channel crossings in 2018.

Security experts and rights groups said the rise reflected the closing of migrant camps in Calais and Dunkirk, in France. From those busy ports, migrants could stow away on trucks, generally a less risky option than crossing in often unseaworthy small vessels.

The authorities have also sought to crack down on smuggling by truck and shipping container, prompting migrants to seek alternative routes like the dangerous Channel crossing.