Independent Anti-Slavery Commissioner Kevin Hyland warned yesterday that “irregular migration” is big business, with people-smugglers charging between £10,000 and £33,000 per person.

But they exaggerate the reliability of their services and the financial rewards attainable, he added.

Agencies were also found targeting legitimate visas for study groups to Britain and “arranging for students to disappear.” Smuggling groups then used legitimate passports to “claim visas for similar-looking Vietnamese nationals.’