Three people have been arrested following an operation at a takeaway in Halton.
Immigration officers visited China China in Tring Road at 6pm on Monday evening.
Staff were questioned to establish whether they had the right to live and work in the UK.
A 47-year-old man from Indonesia and a 41-year-old woman from China were found to have overstayed visas, while a 39-year-old man from China was found to have entered the UK illegally.
The Indonesian man has been detained and the others released on immigration bail while work to remove them from the UK is carried out.
The business now faces a penalty of up to £20,000 per illegal worker unless they can demonstrate that appropriate right to work document checks were carried out, such as seeing a passport or Home Office document.
Immigration officer Andrew Sims said: “We are working hard to identify, arrest and remove people who are abusing the UK’s immigration system.
“All of our operations are intelligence led and information from the public is a vital part of this work.
“I would encourage people with detailed and specific information about illegal immigration to contact us.
“Employers who use illegal labour are cheating the taxpayer, undercutting businesses who play by the rules and depriving legitimate job seekers of employment opportunities.
“Those who ignore the rules, and do not carry out the simple checks to ensure their employees have the right to work in the UK, will face the consequences.”
Anyone with information about suspected immigration abuse can call Crimestoppers on 0800 555 111.