The News of the World lied to a watchdog inquiry into the extent of phone hacking activities by newspapers, the chairman of the Press Complaints Commission (PCC) said today.
Baroness Buscombe said the PCC, a keystone of the system of press self-regulation in the UK, was indescribably angry at being "misled".
The watchdog has faced criticism over its efforts to police the issue, having previously concluded that there was "no evidence" the practice spread beyond one rogue reporter.
"We did not vindicate them (News International). We said there was no evidence at that time and I personally, and the PCC, are so angry because we were misled," she told the BBC's Daily Politics.
"I am the regulator but there is only so much we can do when people are lying to us.
"We know now that I was not being given the truth by the News of the World. Who knows if there are other newspapers that have lied?"
She told the programme: "Words cannot describe how angry I am with this. I am totally angry."
Defending the PCC's past response, she said: "We are doing all we can. We set up in January a review of what took place over those past years. We are holding News of the World to account.
"There is only so much we can do when this is a police investigation about criminal activity. There are criminal laws in place to take care of this."
A statement from the PCC said the commission had "always been clear" in its condemnation of phone hacking.
"The suggestion that people working for a newspaper listened to, and deleted, the voice messages of Milly Dowler will appal and concern everybody in equal measure," it said.
"The PCC is committed to ensuring that such practices are stamped out, and calls upon the newspaper and magazine industry to support its work further to ensure that this is the case.
"Of course, the PCC must work within the existing framework of laws and it is necessary to remember that there is already statutory regulation in the area of phone hacking in the form of the Computer Misuse Act and the Regulation of Investigatory Powers Act.
"Those laws, which carry prison sentences and are enforceable through the police, did not stop the dreadful actions of certain individuals in the first part of this century.
"It is also wrong to judge self-regulation in 2011 based on the legitimate condemnation of practices that took place some time ago.
"It is right to use this terrible moment in British journalism as a catalyst to improve the reach and range of the PCC.
"We are committed to working with the industry, and politicians, to ensure that this can happen.
"At this point, it would not be correct for us to comment further.
"There is a live police investigation, which must be allowed to take its course and which is actively pursuing inquiries about these claims.
"Needless to say, we will be requiring News International to answer publicly in response to these allegations as soon as the police investigation will allow us to do so.
"Our phone hacking review has the broadest remit to ensure that the public can have confidence that wrongdoing has been exposed and illegal and unethical practices have been stamped out."Reuse content