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.
More top news
President Barack Obama recorded a video urging for more to be done to protect the landscape from the effects of climate change.
David Cameron is facing growing pressure for the UK to take in more of the many thousands of migrants fleeing to Europe.
China has put on its biggest display of military might in a parade to commemorate victory over Japan in World War Two.