The government of Prime Minister David Cameron was engulfed Friday in a rapidly spreading scandal after his former spokesman was arrested on allegations that his staff hacked into cellphone accounts and bribed police for confidential information when he served as top editor of a popular tabloid.

Just a year into office, Cameron fought to assure angry Britons that he was as appalled as they were by allegations that one of Rupert Murdoch’s flagship newspapers had snooped on citizens by using the tabloid “dark arts.”

The Conservative Party leader announced two separate inquiries into the revelations, saying that “no stone will be left unturned” and that “the investigation will go where it goes.”

At a news conference, reporters asked Cameron how he could have hired a former tabloid editor as the public face of his administration. Andy Coulson resigned in January after persistent revelations that his former newspaper had engaged in widespread phone hacking.

Fast-spreading scandal

The arrest of Coulson, former spokesman for 10 Downing Street, was a stunning development in a fast-moving story that has rocked the British media and political world. It follows the announcement Thursday that the salacious News of the World will publish its final edition Sunday after 168 years in print.

Leaving a south London police station late Friday night, Coulson, 43, told a scrum of jostling reporters that there was a lot he wanted to say, “but I can’t.”

Coulson was editor of the News of the World when the newspaper allegedly engaged in illegal hacking of the cellphones and voice mails of aides to the royal family, celebrities, politicians and relatives grieving the loss of loved ones in the London transit bombings in 2005.

In his remarks, the prime minister said he remained a loyal friend of Coulson’s but promised to support both the police investigation and others seeking to learn the extent of the alleged eavesdropping. Police sources say as many as 4,000 mobile phone accounts might have been hacked.

Cameron also faced questions about his ties to James Murdoch, and his father, Rupert, whose newspapers loom large in British politics. The Murdochs’ News Corp. is trying to purchase the remaining 60 percent of the United Kingdom’s most popular pay-TV satellite channel, a move that requires government approval.

Coulson has denied any knowledge of the hacking. Top executives at News Corp. initially described the illegal snooping as the work of a rogue reporter and a private investigator.

That reporter is Clive Goodman, 53, the former News of the World royal reporter, who was arrested Friday on “allegations of corruption.” Goodman was jailed for four months in 2007 after he pleaded guilty to hacking into private phone messages in connection with pursuing stories about the British monarchy.

The scandal emerged after Goodman wrote stories in 2005 about Prince William that contained details about the young royal arranging a meeting with his knee surgeon, something known to few people. The articles raised alarm bells in the royal household.

Police on Friday raided the offices of another British tabloid, the Daily Star, where Goodman currently works, and searched for files.

“I had given him a second chance,” Cameron said of Coulson. “The second chance didn’t work. He had to resign all over again.”

Cameron’s critics in Parliament have suggested the prime minister is either incompetent and didn’t know that Coulson was implicated in illegal activities, as is alleged, or didn’t care and hired him anyway.

Labor Party leader Ed Miliband urged Cameron to apologize to the nation for an “appalling error of judgment” in employing Coulson and for bringing him “into the heart of the government.”

“I suspect that Cameron half knew,” said Rodney Barker, an emeritus professor of government at the London School of Economics. “He wanted a press man and thought, ‘Coulson is ruthless and will go to any length to serve his master, and I will be his master and he my attack dog.’ ”

CEO under fire

Cameron also criticized his friend Rebekah Brooks, the chief executive of News International, saying that he had heard reports she had offered her resignation.

“In this situation, I would have taken it,” Cameron said.

Brooks, editor of the News of the World in 2002 when a murdered 13-year-old girl’s cellphone was allegedly hacked, addressed the paper’s staff Friday, reportedly saying that she will not resign.

According to a purported secret recording of the meeting released on Twitter, Brooks allegedly said: “We know there’s no toxicity attached to you guys in the room — that’s the sadness. It wouldn’t be sad, we wouldn’t all be feeling like this if you guys were up to your neck in it like previous colleagues.”

It was not possible to verify whether the recorded remarks were authentic.

Brooks has come under fire, with critics saying she is skirting responsibility — while keeping her job — as the 200-person staff of the News of the World is sacked.

The News of the World has a long and colorful history as Britain’s premier scandal sheet. For many decades, its specialty has been its coverage of celebrities, athletes and politicians, particularly those involved in sex scandals.