The chairman of Daily Mail and General Trust, Lord Rothermere, has expressed "regret" about the way the Mail covered the Madeleine McCann disappearance story, but told the Leveson inquiry: "I let my editors edit, however uncomfortable it makes me feel."
Giving evidence at the inquiry this morning, Rothermere said: "At times, inevitably the paper will do things which makes one feel uncomfortable."
He said journalists covering the Madeleine McCann story were "unfamiliar with the way in which the Portuguese media and police operate", adding: "A number of allegations were made which were followed up in our newspapers which we regret and when the McCanns complained we immediately rectified and gave them compensation. It's a regrettable occurrence but it is the nature sometimes of journalism to do that.
"I don't believe our newspapers set out to wilfully upset the McCanns. They were reporting on briefings they had which they believed to be true and when they realised they made a mistake they rectified it."
Rothermere also discussed the "mud-slinging" between his newspaper group and Richard Desmond, the owner of the Express. He told the inquiry: "(Mail editor) Paul Dacre felt very strongly that Richard Desmond should not own the Express newspapers - that the government should have used the fit and proper person clause to stop him doing it. He expressed that point of view forcibly through the newspaper.
"Richard Desmond responded by digging up everything he possibly could about my family, which we largely took in our stride. This unhealthy antagonistic relationship was not in the interests of the readers and not in the interests of the industry."
He added: "I don't believe there was a truce and the proof is in the pudding. The Express continued to attack me."
Rothermere said there was a general public perception "that self-regulation has not worked".
He told the inquiry: "I believe that the establishment and many members of the public do not believe that self-regulation has not worked, and so therefore it has not worked. The form of the PCC has not been able to establish a level of trust and faith that is necessary for it to function properly. That is almost certainly the case.
"I don't know of many instances where the PCC has asked a newspaper to do something and it has not complied. So in that respect it has worked. It is not the job of the PCC to administer the law."
Lord Justice Leveson said: "Another of the concerns that I have to address is whether newspapers really do hold each other to account. It is interesting that if the judiciary make a decision then within hours those who disagree with it will make their disagreement very clearly felt.
"But it doesn't very often happen that the press hold each other to account and we have got this example that the whole business of interception of voicemails really dies a death until it so happens that the Guardian picks it up and runs with it pretty vigorously and nothing much happens.
"Then it's the New York Times that picks it up. Who actually is watching the press themselves are doing? Do you think the press have failed in that regard - to keep an eye on everyone else?"
Rothermere replied: "The Guardian certainly surfaced much of what's now become public knowledge. I would say that's an example of the press regulating itself to a degree. The Guardian had to work very hard indeed and they have my admiration.
He added: "I think it's the job of our institution to hold people accountable, including members of our institution."