"If that had happened, I would have known about it," Murdoch said in an interview, The New York Times reported Thursday.
The head of Scotland Yard, Paul Stephenson, said he assigned an investigator to look into the allegations after The Guardian reported police found evidence "thousands" of cell phones were tapped by private investigators used by reporters from News of the World, a News International newspaper.
Andy Coulson, Conservative leader David Cameron's director of communications, was deputy editor and editor of the News of the World when the alleged phone tapping occurred, The Daily Telegraph reported.
Cameron defended Coulson Thursday, The Guardian reported.
"It's wrong for newspapers to breach people's privacy with no justification," Cameron said. "That is why Andy Coulson resigned as editor of the News of the World 2 1/2 years ago."
The Press Complaints Commission said it was considering reopening its 2007 investigation into phone hacking by newspaper journalists, The Guardian said. The panel also said it would investigate any new allegations about potentially illegal activity "without delay."
Former Deputy Prime Minister John Prescott said he found it "staggering," that the police may have known about the phone tapping but not informed the victims, including himself.