The year-long scam saw candidates fed answers through a concealed bluetooth earpiece during online CITB tests needed to secure CSCS cards and gain access to construction sites.

Detectives said the gang charged candidates up to £850 each to cheat the exam, generating more than £60,000 over several months.

Police launched the probe after the Construction Industry Training Board raised concerns about organised cheating at test centres across London.

(R-L)Sushil Kumar, Pradeep Sheragar and Jaspal Sani

Officers then worked with CITB and Pearson Professional Assessments, using surveillance, CCTV, call records and location data to identify the suspects and build the case.

At Snaresbrook Crown Court on 31 March, Sushil Kumar, 37, of Redbridge, was jailed for two years and eight months. Pradeep Sheragar, 35, of Redbridge, received a two-year sentence suspended for two years. Jaspal Sani, 43, of Newham, was handed a 15-month sentence suspended for two years.

All three had already admitted fraud by false representation at the same court on 12 January.

The Met said the fraud exposed construction workers and the wider public to risk by helping people with little understanding of site safety secure qualifications they had not earned.

Detective Sergeant Neil Stanley, who led the investigation, said: “Falsifying results is extremely dangerous and poses a risk to site workers across the city. The greed of Sheragar, Sani and Kumar showed a lack of regard to site workers and their safety.”

CITB said it would now work with CSCS to revoke fraudulent test results and withdraw any cards obtained through the scam.

Christopher Simpson, head of CITB Standards Setting Body, said: “Cheats and fraudsters who circumvent these safety critical exams and assessments are putting lives at risk through this type of fraudulent activity, not only the person cheating, but members of the construction industry and public alike.”