Home Secretary Theresa May said that people were naturally asking "who polices the police," and announced an inquiry into "instances of undue influence, inappropriate contractual arrangements and other abuses of power in police relationships with the media and other parties."
Also Monday, Britain's police watchdog said it had received allegations of potential wrongdoing in connection with phone hacking against four senior officers — Stephenson, Yates and two former senior officers. One of the claims is that Yates inappropriately helped get a job for the daughter of former News of the World editor, Neil Wallis.
The Independent Police Complaints Commission said it was looking into the claims.
Yates said he had done nothing wrong.
"I have acted with complete integrity," he said. "My conscience is clear."
Cameron is under heavy pressure after the resignations of Stephenson and Yates, and Sunday's arrest of Murdoch executive Rebekah Brooks — a friend and neighbor whom he has met at least six times since entering office 14 months ago — on suspicion of hacking into the cell phones of celebrities, politicians and others in the news and bribing police for information.
He trimmed another seven hours from his itinerary — having already jettisoned stops in Rwanda and South Sudan — as his government faces a growing number of questions about its cozy relationship with the Murdoch empire during a scandal that has taken down top police and media figures with breathtaking speed and knocked billions off the value of Rupert Murdoch's global media empire.
Parliament was to break for the summer on Tuesday after lawmakers grilled Murdoch, his son James and Brooks, in a highly anticipated public airing about the scandal. Cameron, however, said lawmakers should reconvene Wednesday "so I can make a further statement."