A Northern Ireland journalist has resisted police demands for her to hand over confidential information about the Real IRA.
Suzanne Breen, Sunday Tribune Northern Editor, has been threatened with legal action if she doesn't give up phones, computers, discs, notes and other material linked to two articles she has written on the paramilitary organisation.
Officers gave her seven days to comply after visiting her Belfast home on Monday. They want details about the Real IRA's claim of responsibility for the murder of two soldiers at Massereene army barracks, Antrim, in March and an interview with a senior Real IRA representative in which the group admitted killing Provisional IRA informer Denis Donaldson and threatened to murder more soldiers and police.
National Union of Journalists General Secretary Jeremy Dear said: "If the police and security services believe they can force journalists to become part of intelligence-gathering operations the very future of independent journalism will be put at risk.
"An investigative journalist's job is to expose the truth.
"They can only do that if their sources know they can speak openly and in confidence."
Sappers Mark Quinsey, 23, of Birmingham, and Patrick Azimkar, 21, of London, were killed as they collected pizzas outside Massereene barracks on March 7. Prominent republican Colin Duffy, 41, has been charged with the murders.
In today's Tribune, Ms Breen said: "I won't be complying with the PSNI's (Police Service of Northern Ireland) demands.
"Compromising sources undermines the freedom of the press. Journalists and police do different jobs.
"Our role is to put information into the public domain. If a journalist becomes a gatherer of evidence or a witness for the state, they cease being a journalist."
It is understood police invited feedback from the journalist and were not heavy-handed.
A police spokesman said: "The investigation into this atrocity is active and ongoing. Police will use every possible legal means to access information which may assist their inquiries.
"All victims of the Massereene attack, their families and the community expect and deserve nothing less."
Professor Bric Dickson from Queen's University law school said police were proposing a "perversion" of the Terrorism Act.
"It's essential to the running of a healthy democracy that investigative journalists be allowed to go about their perfectly lawful activities without being impeded or constrained by police."
Human Rights organisation the Committee on the Administration of Justice said it was vital police didn't use the Terrorism Act "left, right and centre".
"We should be moving towards a more normal society in Northern Ireland where democracy operates and journalists can carry out their job without fear of police action."
British/Irish Rights Watch director Jane Winter has written to chief constable Sir Hugh Orde to complain.
"Any journalist who allows themselves to be coerced into revealing a source does the whole profession a disservice because they create the public perception that journalists as a whole can't be trusted to maintain confidentiality," she said.