Former News of the World editors Rebekah Brooks and Andy Coulson have been summoned to testify next week before a judge-led inquiry probing phone hacking and news media ethics.
Coulson, who has been asked to appear May 10, worked as Prime Minister David Cameron's spokesman, but stepped down when police launched a new phone-hacking investigation in January 2011.
He resigned as editor of News of the World in 2007, after a private investigator working for the paper and its royal editor were jailed on phone hacking charges.
Both Coulson and Brooks, who will be quizzed at the inquiry May 11, deny knowing the extent of misconduct at the newspaper when they were in charge.
The independent, government-appointed Leveson Inquiry grilled News Corp. chairman Rupert Murdoch last week.
Brooks resigned last summer as chief executive of News of the World's publisher, News International, a subsidiary of News Corp., amid growing outrage over claims of widespread hacking by the Sunday tabloid's staff.
She was editor of News of the World when the voice mail of a missing school girl, Milly Dowler, was hacked by the newspaper in 2002. The teenager was later found dead.
Testifying before a parliamentary committee last summer, Brooks said she was aware the newspaper used private detectives but said she had never paid a policeman or sanctioned a payment to the police.
Brooks is known for her close ties to Rupert Murdoch. She and her husband, racehorse trainer Charlie Brooks, have also socialized with Cameron.
Daily Mail owner Lord Rothermere has also been summoned to appear before the Leveson Inquiry next week, as has Martin Clarke, editor of the Mail Online.
Both Brooks and Coulson have been arrested and released on bail by police investigating allegations of illegal phone hacking and corrupt payments to police and public officials.
Dozens of others, including journalists, police officers and public officials, have also been arrested and released on bail in connection with the inquiries. No one has been charged.
The latest arrest Thursday was of a former police officer suspected of taking improper payments.
The 57-year-old, who retired several years ago, had served in the Metropolitan Police Service's Specialist Operations command based in central London, police said.
The Special Operations unit deals with counterterrorism, security -- including for airports and Parliament buildings -- and protection for the royal family, ministers and public officials.
The Metropolitan Police declined to say in which area the suspect had worked. He was released on bail Thursday afternoon.
His arrest was the result of information provided to police by News Corp.'s Management Standards Committee, an internal panel set up to probe claims of misconduct by News Corp. employees, police said.
Rupert Murdoch faced fresh criticism Tuesday when a UK parliamentary committee examining phone hacking at the News of the World said he was "not a fit person" to run a major international company.
However, News Corp.'s board of directors strong endorsed him Wednesday, expressing "its full confidence in Rupert Murdoch's fitness and support for his continuing to lead News Corporation into the future as its chairman and CEO."