The British Defence Secretary, Mr Geoff Hoon, has obtained an injunction against the Sunday People newspaper to prevent it identifying a British mole still operating at the highest level within the IRA.
Last week's edition of the paper alleged that a Catholic pensioner, Mr Francisco Notorantonio, who was shot dead by the Ulster Freedom Fighters in October 1987, was killed on the orders of a high-ranking British intelligence officer to protect the mole's identity.
The story also alleged that a number of officers at the highest level were under investigation for "orchestrating dozens of other loyalist killings".
The Commissioner of the London Metropolitan Police, Sir John Stevens, is conducting an investigation into allegations of security-force collusion with loyalist paramilitaries.
Mr Notorantonio was known to be an "old republican" who had been interned in the 1940s and 1970s but had ceased to be actively involved with any organisation when he was shot dead. One of his daughters yesterday said she had originally believed he was killed like so many other "innocent Catholics, in the wrong place at the wrong time".
"But the people who came in to kill him were very professional, so professional I thought it was the SAS . . . If I had any doubt that the story was just allegations I could have been fobbed off. After all this [the injunction against the Sunday People], I cannot be fobbed off and my family cannot be fobbed off," she told UTV.
In a statement, the Sunday People said it was disgusted with the court ruling. "We have been gagged by the [British] government and the security services and we can't even tell you why.
"Earlier this week, and without notice, the British Secretary of State for Defence tried to silence us by taking us to the High Court in London . . . On Friday, we fought back and applied to the same judge to change the order.
"Incredibly, he has ruled you [members of the public] aren't allowed to know anything about his latest judgment."
The editor of the paper's Ireland edition, Mr Greg Harkin, said he could not believe he was not allowed to tell readers what had occurred in court given that the article "clearly contained matters of enormous public interest".
A spokesman for the MoD would not comment on the matter yesterday, but nationalist politicians in the North criticised the Defence Secretary's move.
An SDLP spokesman called for a "forum" in which these "extremely serious allegations" could be fully investigated, while a Sinn Fein MLA, Mr Gerry Kelly, said the development was proof that the British government's "dirty war" in Ireland was still ongoing.
The Irish secretary of the National Union of Journalists, Mr Eoin Ronayne, described the development as an "outrageous interference" which "smacked of former Eastern bloc-style censorship".