The move has come after Building columnist John Smith found he was able to get a CSCS card through an agency that supplied false references, and wrote about it (6 February, page 33).
The CITB asked the police to investigate the case but has decided not to proceed with a prosecution, as there was no evidence of criminal intent. The CITB said all individuals that were involved in obtaining a card from the agency had agreed to reapply using genuine references.
The CITB said the police were investigating the use of false CSCS cards in the south of England.
The board said it was a criminal offence to make and to carry fraudulent cards and added that CSCS was considering a prosecution against one suspected supplier.
George Brumwell, the chairman of CSCS, said he had acted swiftly to try to prosecute in cases where fraudulent activity has taken place. He said: "We are urging employers and site managers to let us know if they come across any incidences of suspected malpractice."
To check the validity of a CSCS card, contact 01485-578777.