Law firms, insurance companies and financial services providers dominate a list of more than 100 companies from outside the media linked to illegal activities by rogue private investigators.
The list of more than 102 names - which also includes two celebrities - has been passed to the Home Affairs Select Committee by the Serious Organised Crime Agency (Soca).
Twenty-one law firms, nine insurers and eight financial service companies are on the list, the committee revealed.
Soca's list was handed to the committee on the grounds the names mentioned would not be released.
Committee chairman Keith Vaz told Sky News: "These organisations and individuals may well in the future be the subject of investigation by the Information Commissioner or the Metropolitan Police.
"What, very helpfully, they have agreed we can do is release the categories."
The Metropolitan Police allegedly holds a list of 200 more companies and individuals who may have used rogue private investigators to steal personal information.
Operation Tuleta, set up by the Metropolitan Police alongside a probe into alleged phone hacking by journalists, investigates claims of computer hacking and privacy breaches.
As well as hacking, private investigators are known to have accessed information through blagging - faking a person's identity to draw information from official sources.
James Clappison, a member of the Home Affairs Select Committee, said: "Some of these private investigators have been involved in very serious violations - hacking into computers, intercepting telephone conversations and getting people's personal details."
A spokesman for the Metropolitan Police said it was "aware of companies and individuals outside of the media industry who are suspected of having committed criminal offences".
He added: "We are not prepared to provide any information that may lead to the identification of any individual or company who may be of interest to that investigation.
"Tuleta is a complicated inquiry and we are not prepared to give a running commentary. The investigation will proceed without bias and will go where the evidence takes us.
"As this investigation is ongoing, and there have been a number of other investigations directly linked to the work of private investigators over a number of years, we do not hold any single definitive list of clients."