Clive Goodman, the royal editor of the News of the World, has pleaded guilty and could face jail for plotting to intercept private phone messages involving the royal family.
Goodman, 48, from Putney, south-west London, was arrested on August 8 after a police investigation into allegations of phone tapping at Clarence House. Members of the Prince of Wales's household claimed there had been security breaches in its telephone network.
In the dock at the Old Bailey with Goodman was former AFC Wimbledon footballer Glenn Mulcaire, 35, also from south-west London, who admitted the same charge.
Mr Mulcaire further admitted five charges of unlawfully intercepting voicemail messages left by a number of people, including publicist Max Clifford and Elle Macpherson.
The charges, under the Regulation of Investigatory Powers Act 2000, date to interceptions between February 16 2006 and June 16.
The conspiracy charge, under the Criminal Law Act, relates to conspiring to intercept voicemail messages between November 1 2005 and August 9 2006.
Mr Justice Gross told the pair: "All options are open. It is an extremely serious matter."
They will be sentenced on a date some time after January 12.
During the hearing at the Old Bailey this morning, Goodman's defence lawyer John Kelsey-Fry QC said that Goodman wanted to apologise publicly and unreservedly to those affected by his actions, Prince William, Prince Harry and the Prince of Wales.
Mr Kelsey-Fry said: "Now that Mr Goodman has entered his plea of guilty, he wishes, through me, to take the first opportunity to apologise to those affected by his actions.
"The prosecution case refers to a gross invasion of privacy and Mr Goodman accepts that characterisation of his acts. He apologises to the three royal members of staff concerned and to the principals, Prince William, Prince Harry and the Prince of Wales."
Dressed in a dark wool suit, Goodman spoke only to confirm his name and to confirm his guilty plea.
Mr Mulcaire issued a similar apology to Goodman, including to those named in the charges he admitted.
Simon Hughes MP, Gordon Taylor, the chief executive of the Professional Footballers Association, and Andrew Skylet, agent for England defender Sol Campbell, also were identified as people who had messages intercepted by Mr Mulcaire.
Staff at the Prince of Wales' residence became suspicious after two of Goodman's stories in the Sunday tabloid in 2005 detailed extracts of private staff phone messages concerning princes William and Harry.
Anti-terror police investigated the allegations and searched Goodman's home as well as properties in Chelsea, Sutton and the offices of the News of the World.
Goodman has been suspended by the News of the World since his arrest by officers from the Royal Protection Unit, and now faces the end of his career.
He admitted conspiracy to intercept communications to get royal scoops for the News of the World.
Glenn "Trigger" Mulcaire was a player and assistant manager with AFC Wimbledon in 2002.
He runs Nine Consultancy, a Chelsea-based firm described as a "crisis management consultancy".
Both men remain on unconditional bail. The probation service is to prepare reports on them before sentencing.
· To contact the MediaGuardian newsdesk email editor@mediatheguardian.com or phone 020 7239 9857. For all other inquiries please call the main Guardian switchboard on 020 7278 2332.
· If you are writing a comment for publication, please mark clearly "for publication".