Former British prime minister Gordon Brown charged Tuesday that Rupert Murdoch’s newspapers hired “known criminals” to obtain information about him, and a senior police official said he was sure his own phone was hacked, as a mounting scandal threatened to further damage Murdoch’s media empire.

Amid a steady stream of fresh allegations against the media mogul’s newspapers, Parliament summoned Murdoch for questioning next week along with top executives overseeing his British subsidiary: his son James Murdoch, 38, and Rebekah Brooks, 43, a former editor of two of his papers.

The scandal, which began with phone-hacking allegations against Murdoch’s best-selling Sunday tabloid, the News of the World, showed signs of spreading to other newspapers published by News International, the British arm of his flagship News Corp. In addition to News of the World, which Murdoch closed after Sunday’s issue in response to the scandal, News International publishes the Times of London, the Sunday Times and the daily tabloid the Sun.

In an interview Tuesday with the BBC, Brown charged that the Sunday Times had paid “elements of the criminal underworld” to do “the most disgusting of work,” not only against him but against “completely defenseless” people. Brown also suggested that the Sun had illegally obtained medical records showing that his son had cystic fibrosis, leading to a story in the tabloid disclosing the illness. News International responded Tuesday that the Sun obtained the information from a legitimate source and asked Brown to provide “all information concerning these allegations” so that it could “investigate these matters further.”

His voice trembling with emotion at times, Brown told the BBC: “My tax returns went missing at one point. Medical records have been broken into. I don’t know how all this happened but I do know ... that in two of these instances there is absolute proof that News International was involved in hiring people to get this information. ... And I do know also that the people that they work with are criminals, criminals with records, criminals who sometimes have records of violence as well as records of fraud.”

In a separate BBC interview, Prime Minister David Cameron said the story about Brown’s son appeared to be another example of an “appalling invasion of privacy.”

The assistant police commissioner at Scotland Yard, John Yates, told Parliament meanwhile that he was “99 percent certain my phone was hacked during the period of up to 2005-06.” He said he did not know who was responsible, and he emphatically denied that the hacking had anything to do with his 2009 decision to drop a three-year-old criminal investigation of alleged phone hacking by News of the World. Yates rejected as “despicable” suggestions that he killed the probe because he feared that the tabloid would publish details about his personal life.

Yates also strongly denied that journalists had ever paid him for information but conceded it was “highly probable” that some of his officers received such payments.

The testimony came a day after fresh allegations emerged that Murdoch’s journalists not only targeted Brown, who stepped down as prime minister last year, but may have obtained private voice-mail messages of Prince Charles and his wife, Camilla.

Investigations by the BBC and the Guardian newspaper suggested that illicit practices ranged beyond the feisty world of News Corp. tabloids and included journalists acting on behalf of the more prestigious Sunday Times.

“Gordon Brown has now been informed of the scale of intrusion into his family’s life. The family has been shocked by the level of criminality and the unethical means by which personal details have been obtained. The matter is in police hands,” Brown spokeswoman Nicola Burdett said in a statement Monday.

Other News Corp. journalists, the BBC said, sought to buy the personal phone numbers of the royal family, leading the broadcaster to question whether even Queen Elizabeth’s phone might have been hacked.

Murdoch flew to London in an attempt to personally manage what is quickly becoming one of the most serious crises in the history of the world’s second-largest media conglomerate — a global network of newspapers, film studios and television stations, including U.S.-based Fox News.

Murdoch over the weekend shuttered the 168-year-old News of the World tabloid, seeking to quell a growing fervor here. Though years in the making, the scandal — at first thought to be limited to police bribes and the hacking of voice mails of celebrities and sports stars — turned into a full-scale crisis last week amid revelations that News of the World had also targeted average British citizens.

British Deputy Prime Minister Nick Clegg on Monday suggested that shutting down one newspaper would not be enough. After meeting with the parents of Milly Dowler, a 13-year-old abducted and killed in 2002 whose case was complicated by News of the World phone hacks, Clegg called on Murdoch to drop his $12 billion bid to expand his holdings here by taking over full ownership of British Sky Broadcasting, the nation’s most lucrative satellite broadcaster. News Corp. owns 39 percent.

Such a move could thwart News Corp.’s plans to consolidate its position as the dominant voice of conservative Britain by adding a highly profitable and politically influential asset to its portfolio. A successful takeover of the company was also viewed as a key stepping stone for James Murdoch on the road to running his father’s empire one day.

“The Murdochs have ruled the roost here in this country for 30 years,” said Claire Enders, chief executive of London media researchers Enders Analysis. “This is absolutely seismic for their empire.”

Indeed, the BSkyB deal, which has been in the works for months, is suddenly in doubt, analysts say. In an apparent attempt to buy time, News Corp. on Monday withdrew a pledge to spin off the Sky News channel as part of the deal, effectively forcing the government to refer the takeover to competition authorities for a potentially lengthy review.

The move came after the opposition Labor Party said it would present a motion against the BSkyB takeover in Parliament on Wednesday. Such an action could divide Britain’s coalition government of Conservatives, known for their close ties to News Corp. journalists, and Liberal Democrats, who have often been their targets. Some Liberal Democrats have indicated they may break government ranks to vote with Labor to block the takeover.

After initially plummeting more than 7 percent in heavy London trading, shares of BSkyB closed down more than 5 percent Monday.

“Look how people feel about this. Look how the country has reacted with revulsion to the revelations,” Clegg told reporters. He called on Murdoch to “do the decent and sensible thing and reconsider — think again — about your bid for BSkyB.”

The Guardian also reported that police have warned Buckingham Palace that Charles and Camilla were among several members of the royal family who might have had their voice mails hacked. The Guardian said that Brown was targeted during his years as chancellor of the exchequer — Britain’s equivalent of treasury secretary — as well as while he was prime minister.

In one of many incidents reported by the newspaper, Brown’s tax filings were apparently hacked from his accountant’s office. In another, someone reportedly working for the Sunday Times posed as Brown to obtain his private bank information, the paper said.

Meanwhile, the scandal continued to put pressure on Murdoch’s inner circle and on Cameron, a Conservative who is facing questions over his party’s political ties and his personal connections to News Corp. officials.

Andy Coulson, a former News of the World top editor who was arrested Friday in connection with the hacking scandal, was Cameron’s communications officer until he resigned under pressure in January. Cameron is also a personal friend of Brooks, a former top editor of News of the World and the current chief executive of News Corp.’s British operations who is now facing calls to step down. Brooks and Coulson have maintained that they had no knowledge of illicit news-gathering.

Yet the reports that Brown — Cameron’s opponent in last April’s elections — had also been a target of News of the World only escalated calls for Cameron to provide more details of his relationship with News Corp. officials. Cameron has already called for two independent investigations into the scandals, and has also denied receiving specific information indicating that Coulson had been involved in any wrongdoing before hiring him as a communications director.

Nevertheless, Labor Party leader Ed Miliband said Monday that the government must move up the timetable for announced independent inquires into the scandal. Cameron’s account of what he knew “does not add up,” he said.

“What I'm saying is the prime minister has a whole series of unanswered questions on this issue,” Miliband said.

Branigin reported from Washington. Special correspondents Karla Adam and Eliza Mackintosh contributed to this report.