On Monday, a Police Service of Northern Ireland officer arrived at my Belfast home with a letter. Detectives wanted my computer, disks, notes, phone, and any material relating to stories I'd written about the Real IRA.

I was given three days to comply. If I didn't, they'd seek a court order under the Terrorism Act. I won't be complying. The duty of a reporter to protect their sources is part of the National Union of Journalists' code of conduct. It doesn't matter whether those sources are police, paramilitaries, politicians, or civil servants.

Compliance would also destroy my livelihood and life. No organisation or individual with sensitive information would trust me again. If I did what the PSNI wants, my life would be in imminent danger. The Real IRA is utterly ruthless.

It shoots men delivering pizza to the security forces. It doesn't grant special status to journalists who, in its eyes, "collaborate". My Sunday Tribune stories related to the murder of two British soldiers at Massereene in March and that of Denis Donaldson three years ago.

Both investigations are matters of great public importance. But it's the job of police, not journalists, to bring those responsible to justice. The information I have about both attacks was printed in this newspaper. It's in the public domain.

I've no other information to substantially advance the police investigation. The Real IRA don't tell journalists their gunmen's identities. I wasn't allowed to record my interview.

The resurgence of republican violence has undoubtedly placed the PSNI under immense pressure. But, in pursuing the Sunday Tribune, they're engaged in a charade at best, harassment at worse.

Protection of sources is vital for press freedom in a democracy. Compromising sources undermines the press's role as a public watchdog and damages its ability to provide accurate and reliable information.

In our Easter Sunday edition, we printed a Real IRA statement calling Martin McGuinness a traitor, admitting Denis Donaldson's murder, threatening young PSNI recruits, and warning that dissidents would "strike at the British occupation forces wherever and whenever we decide".

Targeting the messenger

We reported that this statement would be read out by "a member of the republican movement" at the 32 County Sovereignty Movement commemoration in Derry city cemetery the following afternoon.

We didn't attempt to hide the Real IRA's plans – which would undoubtedly have helped the organisation. The police had over 24 hours' warning. Yet, they did nothing. A masked man in full combat gear appeared and, to loud cheers, read out the statement.

There wasn't a PSNI officer, nor helicopter, in sight. So the police didn't see fit to take immediate action to arrest a paramilitary in a balaclava making chilling threats, but want to pursue a journalist for writing a story.

They're targeting the messenger, rather than those behind the message. The PSNI's attitude to the Sunday Tribune since the Massereene killings has been disingenuous.

Immediately after I took the Real IRA's claim of responsibility, I was phoned by gardaí. Days later, a senior PSNI detective requested I make a witness statement and hand over my phone records.

After consultation with my editor, I declined. The detective said he wasn't into "forcing" people to do things.

Ten days ago, another detective invited me to speak to police unofficially. If I didn't like their questions, I was under no pressure. I could walk out of the meeting. I declined the offer. The PSNI showed their true intentions with the letter from Detective Chief Superintendent Derek Williamson.

The police's attitude over the years to interviewing paramilitaries and claims of responsibility has been inconsistent. I took the INLA's claim for the murder of an alleged Derry drug dealer. The PSNI haven't pursued that. Is there a hierarchy of life, with the death of soldiers above that of a civilian?

The 'disbandment' of the RUC was meant to usher in a new enlightened area of policing in the North. Not always so. Six years ago, the PSNI raided the home of journalists Liam Clarke and Kathryn Johnston over an alleged breach of the Official Secrets Act.

Political judgements

In their biography of Martin McGuinness, they'd published his conversations with Mo Mowlam. The five-hour search of their home was intrusive and intimidating. Heavily armed police emerged from four armoured vehicles and unmarked cars.

There was no female officer, even though Johnston's personal belongings and her children's rooms were ransacked. Johnston was arrested, although no child-care arrangements were in place for her eight-year-old daughter.

Even today, Johnston is highly emotional describing "this violation". Police inexplicably took away the children's games, the couple's bank statements, photographs, and pay-slips. During the five-hour search, the couple were banned from phoning a solicitor, employer, or friends.

It seems police make political judgements to act in certain cases and to ignore others. I've previously taken Provisional IRA claims of responsibility during its campaign. I've conducted many interviews with its representatives but have never been approached by police.

In 1993, a week after the UDA killed six Catholics, I interviewed its 'Inner Council' for the Irish Times. They declared Irish government ministers and SDLP leaders "legitimate targets".

They said civilian casualties were "inevitable in a war situation" and spoke of bombing the Republic. Unlike the Real IRA, UDA figures openly offered personal details for publication. One disclosed he'd been in the British army but had left aged 20. Police never contacted me about any of this.

In other interviews, some UDA members wore masks, others didn't. Some removed their balaclavas to eat fish and chips. They boasted of murdering Mickey Edwards, a Catholic shopkeeper shot dead in bed with his wife. His six children had run into the room, screaming at their daddy not to die. Again, detectives never even phoned me.

Regardless of the UDA's frightening words, it was right to interview them as it's right to interview the Real IRA. No matter how society abhors paramilitaries - we must know what they're thinking. A new form of Section 31 won't make the Real IRA go away, any more than the original affected the Provisionals.

Indeed, printing the Real IRA interview was welcomed by some of those it named as targets. One informer, Kevin Fulton, wrote a letter of thanks to this newspaper. Informers Raymond Gilmour and Marty McGartland also appreciated our interview. They contacted MI5 to discuss their security. Without our story, the security services mightn't even have informed them of the threat.

Ten years ago, the PSNI pursued the Sunday Tribune's then Northern Editor, Ed Moloney, who wouldn't hand over his notes on UDA member Billy Stobie, who was charged with Pat Finucane's murder.

Moloney, who potentially faced five years' imprisonment, courageously refused. He won after a lengthy legal battle. He believed that would "make the authorities think twice before they try to do this against a journalist again". He was wrong.

A decade later, the PSNI is pursuing the same strategy, against the same paper, with a different Northern Editor. It didn't work then, and it certainly won't work now.