London (CNN) -- Prime Minister David Cameron told British lawmakers during a heated session Wednesday that if he had known then what he knows now about his one-time communications director, former News of the World editor Andy Coulson, he would not have hired him.
Cameron faced more than 130 questions as he made a statement to the House of Commons, where members of Parliament grilled him over his relationships with those at the heart of a phone-hacking scandal at the News of the World. That was Britain's largest Sunday newspaper until it was closed July 10 amid a controversy that has riveted Britain and unfolded at a dizzying pace in the past two weeks.
Cameron's appearance in Parliament grew so contentious that legislators were reminded at least twice to be quiet and let the prime minister have his say. It shifted the focus squarely to the political realm, a day after dramatic testimony that focused on the actions of media executives.
News of the World journalists are accused of hacking into the voice mail of potentially thousands of people and of bribing police. The scandal has rattled the foundations of the British press, police and political establishments.
In the House of Commons, lawmakers repeatedly questioned Cameron over his relationship with senior executives at Rupert Murdoch's News Corp., whose British arm, News International, owned News of the World. He also faced sharp questions about his knowledge of the phone-hacking claims and his judgment in hiring Coulson.
The rowdy special session -- which was followed by a general debate on public confidence in media and the police -- came hours after Parliament's Home Affairs committee issued a scathing report about the scandal.
Legislators said in the report that they "deplored" obstruction by News International when lawmakers first tried to probe accusations of illegal eavesdropping by journalists working for Murdoch. The report also criticized police for failing to investigate the case properly.
News International said in a statement late Wednesday that the law firm Harbottle and Lewis had been authorized to answer questions from the police and parliamentary committees.
Earlier, John Whittingdale, chairman of Parliament's Culture, Media and Sport Select Committee, told lawmakers that News International had refused to release the law firm -- which holds papers related to the phone-hacking claims -- from its duty of client confidentiality.
Questioned about his ties to those involved in the scandal, Cameron denied having had "inappropriate conversations" about Murdoch's efforts to take full ownership of British satellite broadcaster BSkyB in meetings with executives of News Corp.
Cameron also insisted that Coulson should be considered "innocent until proven guilty" of phone hacking or of hiding it while at News of the World. If Coulson lied about it, Cameron said, he should be prosecuted.
Coulson, who resigned his government post in January, has since been arrested.
Cameron's decision to hire Coulson left the prime minister "hamstrung by a conflict of interests" when police began investigating allegations of illegal phone hacking by the News of the World, said opposition leader Ed Miliband.
Miliband urged Parliament to ensure that the aftermath of the scandal does not turn out to be "an event where the whirlwind blows through and nothing really changes."
Opposition politicians also accused Cameron of failing to give a straight answer over whether he had discussed News Corp.'s BSkyB takeover bid, which has since been dropped, with officials, including News International's former chief executive Rebekah Brooks.
Cameron, in turn, sought to deflect the pressure by saying the previous Labour government had done nothing to take responsibility for misconduct that occurred while it was in power and was instead presenting a "litany of rather pathetic conspiracy theories to try and win a political game."
The prime minister has formed a committee, composed of civil rights campaigners and former top journalists, to take part in a wide-ranging inquiry into phone hacking and other illegal practices by journalists.
The "torrent of revelations and allegations" has shaken public trust in the media, in police and in politicians, Cameron told lawmakers. "People desperately want us to put a stop to the illegal practices," he said.
The committee will be able to summon witnesses who will testify under oath, he said.
Shami Chakrabarti, director of the human rights group Liberty, will serve as a panel member of the judicial inquiry, Liberty said Wednesday. She called her acceptance of the role "a vote of confidence in the vital role of independent judicial process in times of national difficulty."
Senior police officer Sue Akers said Wednesday that the number of officers and staff working on the latest investigation into phone hacking, known as Operation Weeting, had been boosted from 45 to 60.
The Home Affairs Committee's report, released Wednesday, criticized News International, the police and ministers who failed to pursue concerns raised by previous investigations.
"We are astounded at the length of time it has taken for News International to cooperate with the police but we are appalled that this is advanced as a reason for failing to mount a robust investigation," it said.
Within the Metropolitan Police, it cited former Assistant Commissioner Andy Hayman, who led a previous phone-hacking investigation, and John Yates, who resigned Monday as assistant commissioner after coming under fire over his failure to reopen the investigation.
The committee described Hayman's conduct as "unprofessional and inappropriate," while Yates' decision in 2009 "not to conduct an effective assessment of the evidence in police possession was a serious misjudgment," it said.
The committee's report names neither the elder Murdoch nor his son James, a top executive for News International and News Corp.
Rupert Murdoch left the United Kingdom on Wednesday, News International told CNN, a day after he and his son testified before a different Parliament committee.
Earlier, News Corp.'s Management and Standards Committee, set up in the wake of the scandal, said it had stopped paying legal fees for Glenn Mulcaire -- the private investigator accused of carrying out mass phone hacking for News of the World.
News Corp.'s payment of Mulcaire's fees was raised by members of a parliamentary committee who questioned the Murdochs on Tuesday.
Australian Prime Minister Julia Gillard weighed in Wednesday on the controversy, saying the Australian arm of Murdoch's empire, News Ltd., had "hard questions" to answer.
"When there has been a major discussion overseas, when people have seen telephones hacked into, when people have seen individuals grieving have to deal with all of this, then I do think that causes us to ask some questions here in our country," Gillard said.
Rupert Murdoch e-mailed employees of News Corp. on Tuesday to say he was "shocked and appalled" by the allegations of phone hacking and police bribery by journalists working for his News of the World tabloid.
"I have never tolerated the kind of behaviour that has been described over these past few weeks. It has no place at News Corporation," he wrote after testifying Tuesday.
Both Murdochs said they are not to blame in the scandal, which has raised questions of how much top executives knew about illegal phone hacking and when.
Testy exchanges peppered Tuesday's nearly three-hour session, as the father and son were pressed for answers on who may have authorized or known of reporters' hacking of voice mails.
Asked by one lawmaker, "Do you accept that ultimately you are responsible for this whole fiasco?" Rupert Murdoch responded: "No."
After declaring it was "the most humble day of my life," the elder Murdoch let James Murdoch do most of the talking. When called upon, Rupert Murdoch said he knew little of the day-to-day details of his holdings and that he might hear more from a News of the World editor about extra soccer coverage than a payout to a phone-hacking victim.
Asked whether he had considered resigning, Rupert Murdoch replied: "No, because I feel that the people I trusted, I don't know at what level, let me down and I think they behaved disgracefully, betrayed the company and me, and it's for them to pay."
He added, "I think that frankly I'm the best person to clear this up."
The Culture, Media and Sport Select Committee also heard from Brooks, who had previously worked as the editor of News of the World. She testified she never paid a police officer or sanctioned a payment to the police. Journalists at News of the World are accused of bribing police to get private details about people, including members of the royal family.
She resigned July 15 over the scandal and was arrested and questioned by police two days later. Her lawyer, Steven Parkinson, said Monday his client is not guilty of any crime.
The scandal began with the phone-hacking claims involving reporters from News of the World -- which led its parent company, News Corp., to shut the paper -- and quickly broadened into allegations that journalists had paid police for confidential information.
Murdoch's News Corp. encompasses Fox News, The Wall Street Journal, the New York Post, and Harper Collins publishers in the United States. News International -- a British subsidiary of News Corp. -- owns the Sun, The Times and The Sunday Times in Britain.
CNN's Richard Allen Greene, Laura Smith-Spark, Jonathan Wald, Laura Perez Maestro, Andreena Narayan, Atika Shubert, Anna Stewart, Bharati Naik and Tom Watkins contributed to this report.