Two restaurants in Oxfordshire may have to pay fines of £60,000 for employing illegal workers.
Officers from the Home Office visited Chef Imperial, on High Street in Woodstock, and Mazza Cafe and Restaurant, on Cowley Road in Oxford.
Three people were arrested from Chef Imperial, including two men who had entered the country illegally and a woman who had overstayed her visa.
At Mazza, two men were arrested, one for working in breach of his visa conditions and the other had overstayed his visa.
All those arrested have been placed on immigration bail.
The businesses were served with notices stating that a penalty of £10,000 would have to be paid per illegal worker that was found unless proof is provided that the correct right-to-work checks were carried out.