Immigration officials targeted a shop in Rhymney recently where they found a 29-year-old man working illegally.
On January 10 this year, immigration enforcement officers visited the Premier Store in Church Street, Rhymney.
A shop worker originally from Sri Lanka was arrested for outstaying his student visa.
The business could face a potential fine of up to £20,000 and must now report regularly to immigration enforcement while the case continues.
Richard Johnson, from Immigration Enforcement Wales, said: “I urge anyone with specific and detailed information about suspected immigration abuse to get in touch.”