The NUJ has warned of increasing threats to journalists whose details are being posted on far-right and neo-Nazi extremist websites such as Redwatch.
Redwatch, which has been running for at least two years, lists photographs, addresses and contact details of anti-fascist protesters which the site claims are "for reference purposes only".
A delegation of MPs and union activists met with Government ministers last Thursday to discuss possibly banning the site — which has been accused of inciting violence against anti-fascists.
According to the NUJ, journalists from the Yorkshire Evening Post, Birmingham Post and Mail, the Sunderland Echo, Liverpool Echo, Wales on Sunday and Sheffield Star among others, have appeared on such sites.
Yorkshire Evening Post NUJ father of chapel and anti-racism campaigner Pete Lazenby appears on the site's home page behind what appears to be a gunman's target with the slogan: "Remember places, traitors' faces, they'll all pay for their crimes."
He says he was "verbally attacked" by a known neo-Nazi following his appearance on Redwatch and said newspaper publishers have a "moral obligation" to lend their support to the campaign.
He believes that journalists involved in exposing the criminal activities of extreme right-wing groups as part of their work are "prime targets" on the site, which identifies four other journalists from the YEP alone.
He said: "It's their [publishers'] staff who are being threatened and their weight and prestige would add enormously to the campaign in their staff's interest and as a moral obligation.
"It's happened so often now when appearance on the site is followed by violence that we believe it is responsible for acts of violence."
Most recently anti-fascist campaigner and president of Merseyside TUC Alec McFadden was slashed across the face with a knife at his home in front of his two daughters after appearing on Redwatch.
Tim Bowdler, chief executive of Johnston Press which owns the YEP, said: "It is a matter of concern and one which we are looking at from a company perspective.
"My concern is one which relates primarily to our own journalists and to ensure that their wellbeing is assured.
Having given the matter careful thought we will decide what the best approach is."
NUJ general secretary Jeremy Dear has written to the Newspaper Society, the Society of Editors and Johnston Press, asking them to add pressure on the Government.
He requests the organisations write to the Home Secretary John Reid, Vernon Coaker, the MP for Gedling, as well as Hilary Benn, the MP for Leeds, with a view to taking civil action against those administering the site.
Two years ago a hit-list of targets on a secure email network linked to Redwatch was passed on to the Government, but ministers said it was difficult to take action as the site was hosted in the US.
The Association of Chief Police Officers is currently working with the Home Office to see whether the existing legislative framework is sufficient to close the site which is hosted abroad.
Redwatch's sister site in Poland was closed, setting a precedent.
Redwatch did not respond to Press Gazette's questions.