Former Murdoch employees testified earlier that they told him about the problem.

The younger Murdoch has already been called twice to testify before British lawmakers and resigned from a number of top management positions at British subsidiaries of his father's media empire.

He and his father have always denied knowing about the scale of phone hacking, which police say could have affected thousands of people, ranging from celebrities and politicians to crime victims and war veterans.

Dozens of people have been arrested in criminal investigations into phone and e-mail hacking and police bribery, and police asked prosecutors last week to charge at least eight people.

The suspects include at least one journalist and a police officer, the Crown Prosecution Service said, declining to name them.

No charges have been filed, and the Crown Prosecution Service said it did not know when a decision would be made about charges.

In addition to the Leveson Inquiry and London's Metropolitan Police, two parliamentary committees also are looking into media conduct.

News Corp. shut down The News of the World, its British Sunday tabloid, last summer after public outrage at the scale of illegal eavesdropping its journalists did in search of stories.