The Lib Dems Deputy Leader Simon Hughes told ITV1's The Agenda that he is opposed to the statutory regulation of the press.
He told ITV News Political Editor Tom Bradby: "There must be a strong argument for making sure we don't have a dominant force which runs all the channels so we don't have the choice, they influence too much and set the prices, set the agenda."
"There is the other issue which is about regulation... I'm not for having a statutory system but I am for having a system that says look there will be a fall-back."
Lord Justice Leveson's report is published on Thursday.
The Agenda is on ITV1 at 10.35pm and at 11:35pm in Scotland.
Mayor of London Boris Johnson told ITV News, during a visit to India, that he did not "think it would be right to come up with statutory legislation" ahead of the publication of Lord Justice Leveson's report into press standards.
He added: "You need to have a free press to have a free society. If you want to keep the gutters of public life clean you need a gutter press."
The newspaper claimed he would back a new, tougher model of self-regulation to replace the Press Complaints Commission - but with the threat that a statutory system could be brought in later if matters do not improve.
The Mail on Sunday reports that the judge leading the investigation into media ethics in the wake of the phone hacking scandal was poised to quit following a public attack on the probe by the Education Secretary.
Lord Justice Leveson complained to Downing Street's most powerful civil servant about claims made by Michael Gove that the inquiry had created a 'chilling atmosphere' towards freedom of Press, according to the Mail on Sunday.
In a telephone call with Cabinet Secretary Sir Jeremy Heywood he called for the Tory to be "gagged" and warned the inquiry was being undermined, it said.