Illegal teenage workers were found during immigration raids on two Leeds nail bars.
Two Vietnamese males, aged 15 and 17, were held following Home Office operations at Pretty Nails, in Market Place, Otley, and Summer Nails, in Otley Road, Guiseley, on Thursday.
Two Vietnamese men, aged 25, were arrested in a further swoop at Lisa VN Nails in Huddersfield.
The two teenagers are now with social services. The men are detained pending their removal from the country.
All three businesses were served a notice for employing illegal worker and could face a £20,000 fine per worker unless the necessary evidence of pre-employment checks is provided.
Anita Bailey, deputy director of Home Office immigration enforcement, said: “The message to businesses in West Yorkshire using illegal labour is clear. Our enforcement teams will catch you and if the correct checks have not been carried out you will pay a heavy penalty.
“Illegal working cheats the taxpayer, undercuts honest employers and often exploits some of society’s most vulnerable people.
“We rely on information from the public and I would urge people to report suspected immigration abuse to us.”