A number of reporters attached to Independent News and Media have been told by Gardaí that their safety is at risk from organised criminals.
A statement from INM says the threats are understood to have emanated from criminal gangs in Dublin.
The threats are being made public in order to highlight the danger posed to the media.
INM is working with Gardaí to strengthen security around these journalists and says it is taking every precaution to ensure their safety.
Independent News & Media issued a statement confirming that a number of their reporters had been told by Gardaí that their safety is at risk from organised criminals.
They said: "INM is working with gardaí to strengthen security around these journalists and taking every precaution to ensure their safety. The threats are understood to have emanated from criminal gangs in Dublin."
INM Editor-in-Chief Stephen Rae said: "This is an outrageous threat to the freedom of the press in Ireland and we are taking the threats with the utmost seriousness. The safety of our journalists is of paramount importance.
"It is disturbing that threats of this nature have emerged as we approach the twentieth anniversary of the death of our colleague Veronica Guerin, who was murdered by criminals for exposing their activities. Our media group will not be deterred from serving the public interest and highlighting the threat to society at large posed by such criminals."
Taoiseach Enda Kenny said: "On behalf of the Government and myself I deplore and condemn any threat made to any journalist in this jurisdiction. One of the pillars of a functioning democracy is freedom of speech and in any self respecting society, journalists must be afforded the freedom to go about their jobs without fear of reprisal.
"Those who engaged in the recent killings on our streets will be brought to justice and no resource will be spared in doing so.
"The journalists at whom these threats have been levelled have our full support as do all journalists bravely going about their daily duties."
Seamus Dooley of the National Union of Journalists says the threats are worrying, but reporters will not be intimidated.
He said: "We have learned with shock of threats against journalists working with INM. We are gravely concerned at this latest development, which follows the two recent senseless murders in Dublin.
"Journalists and media organisations will not be intimidated by such threats, which have no place in a democratic society.
Mr Dooley reminded journalists to remain vigilant and to be mindful of their personal safety.
He said: "Employers and editorial managers must continue to provide support, training and guidance to staff and freelance journalists covering dangerous situations.
"We would be reminding all journalists, particularly freelance journalists who work alone, to mind themselves and to take additional precautions.
"That having been said, journalists have faced down threats of intimidation before and we will not be intimidated by these tactics."
Michelle Stanistreet, NUJ general secretary, said: "The union's national executive committee is meeting tomorrow in London and we will be sending be a strong message of support to the journalists. We will also make it clear that intimidation of journalists will not be tolerated."
Minister for Justice, Frances Fitzgerald said: "Journalists play a vital role in our democracy, particularly in shining a light on wrongdoing.
"I regard any threat to the freedom of the press in Ireland as a threat to the State itself. An Garda Síochána are working closely with Independent News and Media to do everything possible to ensure the safety of their journalists."