Prime Minister David Cameron defended himself in a combative session of Parliament on Wednesday over Britain’s phone-hacking scandal, as the opposition raucously questioned his judgment in hiring and associating with executives in Rupert Murdoch’s media empire who are now facing criminal charges.

Cameron cut short an official visit to Africa and flew home to answer questions from lawmakers about the scandal, whose gathering clouds have darkened his 15-month-old premiership. Normally supremely confident, the prime minister at times appeared exposed, declining to deny that he had discussed a major News Corp. business deal in Britain with its top executives. Although he admitted making errors in hindsight, he nevertheless seemed to stand his ground on key allegations and is set to benefit from Parliament’s summer recess, which will silence the House of Commons’ debate on the scandal until September.

The parliamentary debate — at once highly confrontational, immensely personal and occasionally humorous, in the classic fashion of British politics — began just hours after the release of a committee report that accused Scotland Yard of a “catalogue of failures” in its original investigation into phone hacking.

The report also said News Corp. officials had engaged in “deliberate attempts to thwart investigations,” contradicting testimony by Murdoch and his son James Murdoch on Tuesday in which they said the company responded properly to phone hacking by the now-shuttered News of the World tabloid that affected thousands of British citizens.

On Wednesday, Cameron outlined the independent inquiry that will bring experts from the worlds of media, politics and law together for a far-reaching review of press and police corruption, with public hearings set to start this fall. The experts could recommend broad guidelines to limit cross-ownership of media in Britain and redefine the long-cozy rules of engagement for politicians and the press.

The scandal “has shaken people’s trust in the media and the legality of what they do, in the police and their ability to investigate media malpractice, and, yes, in politics and in politicians’ ability to get to grips with these issues,” Cameron said.

Such questions have swirled around Cameron himself. First and foremost, the prime minister is under fire for hiring Andy Coulson — a former News of the World editor — as his director of communications and keeping him on staff even as allegations against him mounted in the press. Coulson was arrested in connection with the scandal this month.

Blasting Cameron and his staff for repeatedly ignoring warnings about Coulson’s role in the hacking scandal, Ed Miliband, leader of the opposition Labor Party, said: “This can’t be put down to gross incompetence. It was a deliberate attempt to hide from the facts.”

Cameron conceded that he had erred in offering Coulson a job. “With 20-20 hindsight, I would not have offered the job,” he said.

Yet Cameron maintained that Coulson should be presumed “innocent until proven guilty,” and he said he would not offer a fuller apology to the nation unless Coulson is convicted. Cameron shot back that Miliband was seeking to distort the facts: “Stop hunting feeble conspiracy theories.”

Nevertheless, Cameron, who won No. 10 Downing Street back for the Conservatives last year, faced further questions over his broader ties to News Corp. executives. He was grilled over whether he had discussed News Corp.’s bid for British Sky Broadcasting with Rebekah Brooks, a personal friend of the prime minister’s and the former head of News Corp.’s British operations. Brooks was arrested Sunday and charged with illegal interception of communication and making police bribes.

Amid the exploding scandal, News Corp. dropped its bid for BSkyB last week. But questions dogged Cameron about a dinner he had with Brooks and James Murdoch two days after oversight of News Corp.’s takeover bid of BSkyB was taken out of the hands of a government minister critical of Murdoch.

Cameron replied Wednesday that he had removed himself from any decisions in the BSkyB deal and had not discussed it with his ministers. But he would not categorically deny that the topic had come up at the dinner or in other meetings with Brooks. Instead, he repeated Brooks’s own words before a select committee on Tuesday that the two had not had any “inappropriate” conversations on the topic.

The opposition also questioned Cameron about revelations that his chief of staff requested in an e-mail last year that the prime minister not be briefed by police about developments in the phone-hacking case. Cameron countered that agreeing to a police briefing on the scandal, especially given Coulson’s role at Downing Street at the time, would have been tantamount to requesting “privileged information.”

AltThough the scandal has damaged Cameron, analysts suggested that unless further details emerge, he is likely to survive this test.

“I think the political agenda will move on quite quickly,” said Robert Oulds, director of Bruges Group, a London-based think tank.

The Home Affairs Committee report released Wednesday stated that News International purposely hindered Scotland Yard’s efforts, including a 2005-06 police investigation that gave rise to the impression that phone hacking had been limited to one incident in which Prince William’s phone was the target. In reality, the hacking was widespread. That probe led to the arrest of two News of the World employees.

But the report also cited police shortcomings, including a failure to examine key evidence. The report accused Metropolitan Police Assistant Commissioner John Yates — who resigned under pressure this week — of “serious misjudgment” for failing to reopen the case after the Guardian newspaper published allegations of far more widespread phone hacking at the tabloid in 2009.

“There has been a catalogue of failures by the Metropolitan Police, and deliberate attempts by News International to thwart the various investigations,” the committee chairman, Keith Vaz, said in a statement.

“The new inquiry requires additional resources, and if these are not forthcoming, it will take years to inform all the potential victims. The victims of hacking should have come first, and I am shocked that this has not happened.”

Special correspondent Eliza Mackintosh contributed to this report.