Cameron government, shaken by expanding News of the World arrests, orders probes

The government of British Prime Minister David Cameron, perhaps Washington's closest ally, is reeling with the arrest today of Cameron's former media adviser in the unfolding News of the World phone-tapping scandal.

Andy Coulson, who served as Cameron's top communications adviser from 2007 to January 2011, and previously as the editor of the Rupert Murdoch-owned highest-circulation British tabloid from 2003-2007, was arrested "on suspicion of conspiring to intercept communications" and "on suspicion of corruption allegations," according to a statement from Scotland Yard.

Cameron, scrambling to try to get out ahead of the scandal's widening criminal scope, summoned journalists to a news conference at Downing Street today in which he took full responsibility for the decision to hire Coulson back in 2007. (You can watch ITN video of Cameron's "hastily arranged" news conference below, as the New York Times' Sarah Lyall and Alan Cowell put it.) Cameron also announced two public inquiries into different dimensions of the scandal, including allegations that the News of the World paid bribes to British police for information.

But Cameron's efforts to distance himself from the scandal so far haven't made much headway, thanks largely to the Conservative Party leader's close personal ties with several top executives in the Murdoch empire. And though he acknowledged that a past police investigation of police bribe-taking went nowhere, Cameron insisted that wouldn't be the case for the newly initiated inquiries.

"There is now a large-scale and well-resourced police investigation," Cameron told journalists at the Downing Street news conference in London today. "Now, of course, in 2006 we did have a police investigation, but we can now see that it was plainly inadequate. This in itself requires investigation."

"And a separate allegation is that police officers took payments," he continued. "So for those worried about the police investigating the police, this has full and independent oversight."

"But I think we should be clear: police investigations only get you so far," Cameron said. "What people really want to know is: What happened? And how was it allowed to happen? That is why the deputy prime minister and I have agreed that it's right and proper to establish a full, public inquiry to get to the bottom of what happened. A judge needs to be in charge so there's no question that it is totally independent and things are done properly."

Critics in England say, however, that no amount of official digging is likely to get Cameron free of the perception that he's implicated, however indirectly, in the tabloid's seamy exploits. "It's a Cameron issue. This is now about him," Steven Fielding, director of the Centre for British Politics at Nottingham University, told Bloomberg News in an interview. "The danger is that this comes to define him in the public mind. Then it becomes the characteristic through which everything he does is viewed."