Acting on intelligence, officers swooped on the construction site and quizzed workers at the site to establish whether they had the right to live and work in the UK.
Officers arrested two Indian men, a 39-year-old who had overstayed his visit visa and a 42-year-old who had entered the UK illegally.
Contractor W.I.S.E. United will be served notice warning that financial penalties of up to £20,000 per illegal worker found will be imposed unless the firm can demonstrate that appropriate right to work document checks were carried out, such as seeing a passport or Home Office document confirming permission to work.
Karen McDonough, head of the Merseyside Immigration Enforcement team, said: “Using illegal labour is not a victimless crime.
“It defrauds the Treasury, depriving vital public services like schools and hospitals of funds, it undercuts honest businesses and it cheats legitimate job seekers of employment opportunities. It also 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.”
Information to help employers carry out checks to prevent illegal working can be found on the Home Office website.