Evidence obtained by Soca revealed 51 of the possible victims "had their personal data fraudulently accessed", Trevor Pearce said in a letter dated August 16.
The information was obtained by private investigators and passed on to 102 companies and individuals on a client list provided to the Home Affairs Select Committee.
In his letter to the committee chairman, Mr Pearce confirmed that no one on the list Soca submitted has been arrested or charged.
A total of 22 law firms feature on the 102-strong list. In his letter, Mr Pearce added "we are not alleging that the individuals or companies named on the list have or even may have committed a criminal offence".