South Derry construction firm FP McCann could face a £225,000 fine for hiring illegal workers in Wales.
It followed a dawn raid on the Shotton Mill site in Deeside, north Wales, on Tuesday March 19, which found five contractors to be working illegally.
Another company, Stockport-based Adana Construction, may have to pay up to £180,000 for employing another four immigration offenders.
They are among the first businesses to be referred for recently increased civil penalty notices for employing the illegal workers, who were all working as subcontracted labourers and steel-fixers.
In all, 12 men and a woman were arrested and will be removed from the UK following the 5am raid. They were all working as subcontracted labourers and steel-fixers.
Immigration Enforcement officers say they descended on the former paper mill – now being turned into a container board factory – in response to allegations from the public.
Seven contractors, from India and Albania, were later taken into custody, while the others were bailed and are required to report to immigration officials.
Officers entered with permission from the site managers, who have since launched an internal investigation.
The operation follows tough action from the Home Office to triple the fines for companies employing illegal workers.
From February, the civil penalty rose to £45,000 per worker for a first breach, up from £15,000, and to £60,000 for repeat breaches, up from £20,000.
HM Inspector Ryan Moore from Home Office Immigration Enforcement said: “Illegal working causes untold harm to communities, puts vulnerable people at risk, defrauds the public purse and undercuts honest employers and job-seekers.
“Our teams will do everything in our power to clamp down on this damaging practice and hit those who cheat our laws in the pocket. This operation was a huge success and I thank our officers who executed it expertly.”
Both companies were issued civil penalty referral notices pending a review of evidence from the site visit and company records.
In October 2019 FP McCann was hit with a £25.4 million fine by the Competition and Markets Authority for its role, alongside two other companies, in an alleged price-fixing cartel stretching over a seven-year period.