The British intelligence service, MI5, has admitted that it unlawfully obtained the data of journalist Vincent Kearney on two occasions.
During a hearing of the Investigatory Powers Tribunal (IPT) in London, it was heard that it obtained the data in 2006 and 2009.
Mr Kearney, who is now RTÉ's Northern Editor, worked for the BBC at the time as Home Affairs Correspondent.
During the hearing, counsel Jude Bunting, acting for the BBC and Mr Kearney, said that the concession from MI5 was unprecedented in tribunal proceedings.
Last year, the BBC wrote to the IPT about alleged PSNI surveillance of phone data linked to Mr Kearney's work at the time.
The tribunal is an independent judicial body which provides the right of redress to anyone who believes they may have been the victim of unlawful action by a public body using covert investigative techniques.
It is believed that this was prompted following information that came to light during a hearing at the IPT last year involving journalists Trevor Birney and Barry McCaffrey.
Last December, the IPT ruled that a covert surveillance operation authorised by the PSNI in a bid to reveal their journalistic source was unlawful.
