The notes of the private investigator jailed for phone-hacking in 2007 will be summarised and made public as part of the inquiry into the scandal.
Glenn Mulcaire’s notebook forms a key part of the ongoing police investigation into the alleged illegal interception of voicemails by the News of the World.
Inquiry chairman Lord Justice Leveson ruled that a summary of the document should be prepared “so that its true significance and extent may be understood”.
He said personal details of those listed as potential targets of phone hacking would not be included in general, although some victims who are already in the public domain or who give their consent could be named.
Names of journalists linked to entries in Mulcaire’s notebook will be anonymised, although they will be placed in bands indicating how senior they were within the News of the World.
Mulcaire was jailed with the News of the World’s former royal editor Clive Goodman in January 2007 after they admitted intercepting voicemail messages on royal aides’ phones.
Lord Justice Leveson made the comments in a ruling on a request from the Metropolitan Police and Crown Prosecution Service (CPS) for him to ensure his inquiry does not affect the criminal investigation into phone hacking.
The inquiry is divided into two parts, the first looking at the culture, practices and ethics of the press in general.
The second part, examining the extent of unlawful activities by journalists, will not begin until detectives have completed their work and any prosecutions have concluded.
Police and prosecutors asked the inquiry chairman not to make public any significant document which has not already been widely reported, and not to take evidence during part one from anyone who is a suspect in the ongoing criminal investigation.
Lord Justice Leveson played down concerns that his hearings could damage any future trial over phone hacking.
“I do not accept that the conduct of part one of this inquiry is likely to cause a risk of prejudice (let alone serious prejudice) to the investigation or any prosecution although I repeat that I will remain mindful of the concerns of the police and the CPS throughout,” he wrote.
The chairman admitted that there might be some “surprising omissions” from the witnesses for the part one hearings because some suspects in the police investigation should not give oral evidence.
But he said: “There will be further opportunities to examine the specifics of the personal conduct of individuals when part two of the inquiry falls to be considered following the conclusion of police investigations and any prosecution.”
The Leveson Inquiry has already held a number of preliminary seminars, and it will formally start on Monday with an opening statement from Robert Jay QC, counsel to the inquiry.