Five internet testing centres for construction skills verification cards have been closed since this summer, it has emerged in the wake of a BBC expose.
The Construction Industry Training Board (CITB) said a further eight centres were under investigation.
A Construction Skills Certification Scheme (CSCS) card acquired with fraudulent qualifications was reportedly used by the BBC to get offers of work at building sites, a school and a power station.
CITB delivery and customer engagement director Carl Rhymer said: “We know card fraud poses a serious threat to the UK construction industry and we are tackling this head-on.
“In July 2014, CITB’s executive team doubled our spend on fraud investigations, which has led to five internet testing centres being shut down, with eight other centres under investigation.
“We are working with CSCS to revoke fraudulent cards wherever they are found, which has in some cases helped trigger investigations into suspect testing centres.
“In addition, we are accelerating our plans to install mandatory CCTV in all testing centres to monitor footage for signs of fraudulent activity, and have launched a series of spot-checks on test centres to act as a deterrent.
“Our intelligence suggests card fraud is focused in a small minority of the 544 testing centres across the country. We continue to work hard alongside partners including the Health and Safety Executive and the National Crime Agency to help stamp out this problem.”
CSCS said it was not responsible for developing qualifications or delivering construction training, but said it took the issue of fraudulent activity “extremely seriously”.
“CSCS is confident the vast majority of cards issued are a result of obtaining a qualification legitimately,” it said in a statement.
“In cases where the awarding organisations inform CSCS that a card was obtained fraudulently, the card is cancelled immediately and action taken against individuals and organisations attempting to deceive construction employers.
“CSCS will continue to share intelligence and work with the authorities when the evidence suggests criminal activity is taking place.”