The names of at least 28 reporters were found in private eye Glen Mulcaire's notebook, the Leveson Inquiry has heard.
Mulcaire, a former private investigator from Sutton, is at the heart of the News Internarional phone hacking scandal.
After being jailed in 2007 over the phone hacking of aides close to the royal family, details have emerged about his other investigations.
The Leveson inquiry into phone hacking was launched this week at the Royal Courts of Justice in London.
Attendees heard how notebooks seized from the disgraced private detective suggested that 28 of News International employees commissioned him to hack phones. Robert Jay QC, a counsel for the inquiry, said at the high court there was evidence to suggest phone hacking was not exclusive to News International, however suggesting management at the company knew what was going on or failed in supervision and oversight.
News International executive chairman James Murdoch told a committee of MPs last week he was unaware of a widespread culture of phone hacking.
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