Loyalist terrorists have issued threats against journalists working for the Sunday Life and Sunday World newspapers.
A number of reporters were visited by police officers in the early hours of yesterday with warnings of imminent attacks.
At least one journalist was told of a planned under-car booby-trap attack, while staff at the two Sunday titles - both owned by Independent News and Media (INM) - were warned they are at risk of immediate attack.
The development comes just weeks after the first anniversary of the New IRA murder of journalist Lyra McKee in Londonderry.
The PSNI is taking the threat seriously and officers have been in contact with the journalists concerned.
It is understood the threats emanate from the breakaway south east Antrim UDA.
Police have confirmed they are "in receipt" of information that indicates a planned and coordinated campaign of intimidation.
Peter Vandermeersch, publisher at INM, said: "We will, of course, work with the police to ensure our staff's safety.
"Threats against journalists should not be tolerated in any free society.
"Today marks the 75th anniversary of the defeat of Nazi Germany and an important element in that victory was ensuring freedom of speech for subsequent generations. It is depressing that thugs still believe they can silence the press through intimidation.
"The Sunday World and Sunday Life will continue to publish stories that shed light in dark corners."
NUJ assistant general secretary Seamus Dooley said the threats were "vile".
He said: "It is the latest in a series of threats in Northern Ireland against journalists but is all the more sinister because it is a blanket threat against two newspapers, titles which have served the people of Northern Ireland fearlessly and often in the face of threats.
"The NUJ, and through us the International Federation of Journalists (IFJ), extends support and solidarity to all journalists employed by the group, for whom this is a distressing time."
Amnesty International also condemned the threats and called for them to be lifted immediately.
Patrick Corrigan, Amnesty International's Northern Ireland Programme Director, said: "Such threats are a disgusting attempt to intimidate journalists from doing their jobs, and constitute an attack on freedom of the press in Northern Ireland. We send our solidarity to the journalists concerned."