The Metropolitan Police has revealed that it has investigated two suspected leaks from officers investigating press leaks.
The force has also revealed that 67 public officials have so far been "dealt" with under Operation Elveden.
The investigation into payments to public official, which had cost £6m minus legal fees at last count, has also seen 33 journalists arrested. Of the known 33, 26 have been charged.
The latest full figures released by the Met, from Feburary, show that the operation has cost £6m to date and involved 69 police staff in 2013/14.
These figures also showed that 82 people had been arrested overall and, of these, 40 charged.
Operation Elveden was set up in the aftermath of the 2011 News of the World phone-hacking scandal.
In October, after it emerged that the Met had used the Regulation of Investigatory Powers Act to secretly obtain the phone records of journalists not suspected of breaking the law as part of a leak investigation, Press Gazette highlighted that the force conducted 38 press leak investigations in the five years to the Leveson Inquiry.
In response, Jenny Jones, Green Party assembly member in the Greater London Authority, asked London mayor Boris Johnson to ask the force how many media leak inquiries have been carried out since these 38.
In response, the Met disclosed the numbers above for Operation Elveden. This is thought not to include all press leak investigations, because the Directorate of Professional Standards (DPS) – and not Operation Elveden – was reported by the Met to have carried out the RIPA investigation into finding the source of The Sun's Plebgate story.
The mayor’s response to Jones said: “Operation Elveden was established to investigate leak related allegations. This relates not only to police officers or staff, but to all public officials who have been paid to leak information to the media.
“Operation Elveden has dealt with an estimated 67 suspects who are public officials (to date).”
It added that the DPS has “independently investigated a further two allegations where it is claimed that officers involved in the investigation of leaks may have leaked information”.