The Construction Industry Training Board helped secure convictions against Baljit Rai, 55, and his two sons, Mandeep Rai, 32, and Daljit Pai, 34, from Littleover, Derby.

The trio supplied illegal workers to sites across the country.

Derby Crown Court heard that Mandeep was “the driving force behind the employment of most workers” and also created fake documents.

He was jailed for seven and-a-half years, while Baljt and Daljit were both sentenced to five years.

CITB’s card fraud team supported the Home Office Immigration Enforcement and the Police in the investigation.

Ian Sidney, CITB Fraud Investigator, said: “CITB takes illegal activity extremely seriously and it is critical that we continue to stamp out the fraudsters.

“I hope this conviction sends a strong message to anyone else that may be taking part in illegal activities, and highlights the seriousness of fraud in construction.

“We simply do not tolerate any fraudulent behaviour that puts people’s lives at risk or brings the industry into disrepute.”