Police face a grilling from MPs over claims that they failed to release details of an investigation which showed that law, telecoms and insurance firms were linked to phone hacking.
The Home Affairs Committee has summoned the Serious and Organised Crime Agency (Soca) to give evidence next Tuesday about documents reportedly showing it knew about the alleged activities six years ago.
Chairman Keith Vaz said in a statement: "Soca have a number of questions to answer about how much they knew about the links between private investigators and the private and public sector and what action, if any, they have taken on the issue.
"We are requesting from Soca a copy of all the information they hold on private investigators and their links with the public and private sector. I have also written to request a list of companies who employed private detectives which obtained information unlawfully."
A Soca report leaked to The Independent suggested law, insurance and telecoms companies routinely used criminals and investigators to hack, blag and steal information on business rivals and members of the public.
One hacker admitted that 80% of his client list was made up of such firms, with the remaining 20% attributed to the media, according to the newspaper.
It is understood the Leveson Inquiry did not deal with the claims because its terms of reference were about the culture, practices and ethics of the press and believed any other matters were beyond its remit.
Prime Minister David Cameron's official spokesman said it was "a matter for police" whether to investigate any allegations of illegal eavesdropping on phone calls. He said: "Clearly, any allegations of illegal activity are cause for concern."
Asked whether the Prime Minister was concerned that Government agencies might have hacked phones, the spokesman replied: "All Government agencies operate in accordance with a strict legal and policy framework. The Government operates within the law."