A total of four employees have been arrested in the Lincoln area for working without UK work permits.
UK Border Agency (UKBA) officers acted on intelligence and visited the Castlegate Indian restaurant and the Chutney Indian takeaway over a period of two weeks.
In the first restaurant, the UKBA arrested a total of three Bangladeshi men who were found to have no right to employment in the UK. As such, the men were subject to a range of checks which revealed that they had overstayed their UK visas.
Two of the men have been detained pending their removal back to Bangladesh. Meanwhile, the third has been temporarily released on UK immigration bail while the UKBA takes steps to remove him from the country.
At the Chutney takeaway, officers discovered a 30-year-old Bangladeshi man without a UK work permit. The man has been arrested and detained pending his removal from Britain.
Rachel Challis of the UKBA's Boston-based team commented: "Any business that takes on a foreign national without permission to work should be aware that they are breaking the law as well as undermining law-abiding employers.
"Rogue employers should be warned that they face heavy fines and could end up in jail."
She added: "We will continue to crack down on companies that employ illegal workers and fail to carry out proper checks on passports and other identity documents."
In order to avoid a fine, which can come to £10,000 for each worker employed illegally, the businesses concerned will need to prove that they carried out the correct UK work permit and passport checks on the men.