A criminal investigation is under way after Border Force intercepted 74 men, women and children who crossed the English Channel in eight small boats on Saturday, the Home Office said.
Home Secretary Sajid Javid said the situation was “deeply concerning”.
“Those who choose to make this dangerous journey across one of the busiest shipping lanes in the world are putting their lives in grave danger – and I will continue to do all I can to stop them.
In December, Javid declared a major incident regarding the Channel crossings following a rise in migrants attempting the perilous journey to reach the UK.
He added: “It is an established principle that those in need of protection should claim asylum in the first safe country they reach and since January more than 30 people who arrived illegally in the UK in small boats have been returned to Europe. We will continue to seek to return anyone who has entered the UK illegally.”
The Home Office said all concerned have undergone medical examinations, and the nationalities of the migrants are being determined.