The Metropolitan Police and Crown Prosecution Service today urged the judge in charge of the inquiry into phone hacking to make sure it does not affect the criminal investigation running alongside it.
In submissions to Lord Justice Leveson's inquiry into media ethics and hacking, they said: "It is inevitable that this inquiry will touch on areas which may have a close connection with the criminal investigation and thus an impact on any subsequent trial, were one to take place."
They added: "We are understandably anxious that nothing should be said or done which might jeopardise either the investigation or trial."
The judge decided today that the inquiry will start on November 14. Its first part will look at the culture, ethics and practices of the press and its relationship with the police and politicians.
The judge, sitting at the Royal Courts of Justice in London, ruled that there should be a preliminary hearing on Monday to discuss how the "interface" between the inquiry and the police investigation should be handled.
The Metropolitan Police and Crown Prosecution Service said in their submissions that the investigations into phone hacking have not been completed, and there are a number of suspects in relation to whom charging decisions have not yet been made.
They said they know the inquiry shares their anxieties "and are grateful for the public reassurance that has been given that it is not Lord Justice Leveson's intention that Part 1 should affect potential criminal proceedings, save in the most tangential sense."
However in discussions with those conducting the inquiry, "it became plain that there might be implications for the criminal proceedings which might not initially be apparent".
As a general proposition, they urged the inquiry not to rehearse any evidence in part one that was likely to prove central to any criminal proceedings.
"This includes, but is not limited to, any investigation as to which individuals were aware of possible criminal activity, and where they sit (or sat) within the hierarchy of any named newspaper. It is our view that these questions may be critical to any prosecution, and would involve the inquiry engaging in a determination which would properly be within the province of a jury."
They asked the inquiry 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 criminal investigation.
They said they were happy to provide such assistance as they could to the inquiry and it might be possible to agree a schedule of uncontroversial facts, time lines and the use of some documents (where such use would not undermine the criminal investigation or prosecution).
The judge told counsel today: "The problem that I have got is balancing the absolute requirement that anybody who is ultimately charged should be able to receive a fair trial, against a competing dynamic that I have to resolve the issues that I have to resolve, probably well before any trial would ever take place."
He stressed that his concern was about culture and ethics, and asked counsel whether "the picture at the News of the World can't be painted in a way that doesn't require over-descent into detail".
He added, referring to the police and CPS: "I don't want to interfere with their investigation and any possible prosecution, and I certainly don't want to prejudice it."
Monday's hearing to discuss this issue will also consider requests by a number of people to give evidence anonymously.
The judge also said he had received invitations to visit newspapers, and was prepared "on a low-key basis, to accede to them".
He added: "I would arrange a visit, low key, with one man on the team, and I don't want presentations, I'm happy to see how it works."
He also wanted to visit at least one regional newspaper, he said.
Counsel raised no objection to the plan.
He told the lawyers: "My job is to see what's going on in the business, and whether the controls in place, such as the PCC (Press Complaints Commission) are sufficient."
And he said: "The whole problem is an industry-wide problem, which has to be solved in a way that works not only for the industry, or profession, whatever you want to call it, but which works for everybody else.
"I don't want to produce a document that people say 'That's unrealistic', and leave it on a shelf to gather dust.
"Over the last 50 years, rather more have been put on the shelf than activated.
"My ultimate aim is to produce a system, whatever it be, that works and has the support of everybody."
Prime Minister David Cameron announced the inquiry in July, following revelations about phone hacking by the News of the World newspaper.