Four employees have been caught without the correct UK work permits in jobs in the UK.
The UK Border Agency (UKBA) found four illegal immigrants working in Watford, two of whom were employed at the McDonald's restaurant in the town.
A 44-year-old and a 20-year-old were found to be working in the restaurant without UK work permits after the UKBA team visited the fast food chain on March 17th.
After conducting checks on the staff, they discovered that the two Algerian men had used fake French documents to secure employment.
Businesses that employ workers without carrying out the correct checks on UK immigration documents and UK work permits can face fines of up to £10,000 for every illegal worker found on their premises.
However, the UKBA was careful to mention that in this case McDonald's will not be subject to the fine because the company conducted the correct UK immigration checks.
Chris Evans, the agency's chief immigration officer, commented: "We do not expect businesses to be experts at spotting fake documents, that's our job, and we are happy to work with law-abiding business to ensure they are not unwittingly employing immigration offenders."
Immigration officers also discovered two other Algerian men employed without UK work permits in the McDonald's outlet after visiting the home addresses of the initial offenders.
A 46-year-old and a 21-year-old were identified as having entered the country illegally.
The UKBA is now working to remove all four of the offenders from Britain.
Mr Evans added: "Illegal working, particularly in the current climate, is a serious offence. These men had conned themselves into positions to which they were not entitled and in the process taken employment opportunities away from genuine job seekers."