A journalists' union has said it is alarmed that a telephone belonging to a Londonderry based journalist has been seized by police.
Officers presented Eamonn MacDermott, who often writes about dissident republicans, with a warrant to confiscate the phone on Thursday.
The NUJ said it was a threat to journalists' rights to protect their sources' confidentiality. The PSNI said it would use all legal methods to carry out investigations.
It said any member of the public who had a complaint to make about police actions could contact the Police Ombudsman for Northern Ireland.
Mr MacDermott believes the seizure relates to a call he received from the Real IRA following a bomb last year.
He stressed the importance of the phone to his career.
"In the course of making a statement previously the police told me that they would be able to access my phone records," he said.
"I know they have accessed my phone records so I asked them why do they need the handset when they already have access to records and can access the records without any difficulty whatsoever.
"All she would tell me was it was part of an investigation and she refused to give me any details.
"I told her that this is my livelihood, as a freelance journalist my phone is my lifeblood, every contact I have is in that phone."
NUJ General Secretary Jeremy Dear condemned the PSNI move.
In a statement, he said: "Eamonn MacDermott is an established freelance journalist working in Northern Ireland, covering sensitive stories and with a wide range of contacts.
"The seizure of his phone and the accessing of his phone records by the police is another attack on the right of journalists to operate in Northern Ireland.
"The right to protect confidential sources of information is compromised when police act in this way and we take this action very seriously."
Last year, the PSNI failed in an attempt to force Sunday Tribune journalist Suzanne Breen to hand over notes on stories she had written about the Real IRA.