The Crown Prosecution Service (CPS) is to announce whether charges will be brought against a number of those arrested as part of the long running investigation into claims that journalists at the now defunct News of the World, hacked into the voicemails of thousands of people.
Eleven current and former journalists and one non-journalist were due to answer bail today, following their earlier arrests as part of the Metropolitan Police's Operation Weeting investigation.
A total of 24 people including 15 current and former journalists have been arrested since the investigation was launched in January last year.
The majority of the arrests came after it was revealed last July that journalists on the News International title had hacked into the voicemail of murdered schoolgirl Milly Dowler.
The subsequent outrage resulted in the closure of the News of the World and the announcement of a public inquiry into the culture and practices of the press, headed by Lord Justice Leveson.
Among those who have been questioned by police are former News International Chief Executive Rebekah Brooks, former News of the World chief reporter Neville Thurlbeck and the newspaper's former head of news Ian Edmonson.
Mr Coulson, who was forced to step down as Prime Minister David Cameron's director of communications amid the mounting scandal, has already been charged with perjury by Strathclyde Police in connection with evidence he gave under oath at the trial of former Member of the Scottish Parliament, Tommy Sheridan.
Mr Mulcaire, who was jailed in 2007 after admitting illegally intercepting messages of members of the Royal Household, has since apologised to the victims of phone hacking.
Mrs Brooks and her husband Charlie have already been charged with perverting the course of justice following allegations that they tried to destroy evidence related to the inquiry.
Alison Levitt QC, the Principal Legal Adviser to the Director of Public Prosecutions, Keir Starmer, will issue a statement regarding the CPS decision at the organisation's headquarters in central London.
Running alongside Operation Weeting is Operation Elveden, a Met probe into allegations of corrupt payments by journalists to public officials.
So far 41 people have been arrested as part of the investigation, while an inquiry into allegations of computer hacking, Operation Tuleta, has seen seven people detained.