Balfour Beatty, Kier and Shepherd are among 14 firms that have been served with enforcement notices following their involvement in the construction blacklist uncovered in March

The action prevents the firms from using the personal data of over 3,200 workers supplied to them by Ian Kerr, who ran the blacklist.

The Information Commissioner’s Office ruled that the companies had breached the Data Protection Act and added that they risked prosecution if they failed to adhere to the notice.

David Smith, deputy information commissioner, said: “Fourteen firms paid for details about workers without them knowing. The individuals were denied the opportunity of correcting what may have been inaccurate personal information.

“We have used the maximum powers available and this action sends a signal that organisations must take the Data Protection Act seriously.”

The firms are: Balfour Beatty Civil Engineering, Construction Northern, Construction Scottish & Southern, Engineering Services (HY), Engineering Services, Infrastructure Services; CB&I UK; Emcor Engineering Services; Emcor Rail; Kier; NG Bailey; Shepherd Engineering Services; SIAS Building Services; and Whessoe Oil and Gas.