Fears are growing that the government will take a tough stance on enforcing new immigration laws.
Tiers 2 and 5 of the much-heralded points-based system coming into force on 27 November, requiring employers wishing to bring certain migrants to the UK to be a licensed sponsor.
Julia Onslow-Cole, partner and head of global immigration at advisory firm PricewaterhouseCoopers Legal, said the UK Border Agency would have little choice but to rigorously enforce the law, because employers self-certified to become sponsors.
"They have no option but to come down relatively hard, or the system breaks down. The only way [to make it work] is to police compliance rigorously," she said.
Lucy Neville-Rolfe, executive director of corporate and legal affairs at supermarket giant Tesco, added: "We are worried about enforcement. If the UK Border Agency decides to show it is being tough, it would be easy to target a retailer with a well-known name."