The directors of Quinn Industrial Holdings have received another death threat, informing them that this is their "last warning".
The threat, delivered to the Irish News, was conveyed to Quinn directors last night by gardaí.
In the letter, which was typed and delivered yesterday, directors were told that this was their final warning.
The anonymous authors told the directors that if they wanted, "we could have killed Kevin very easily", in reference to the attack on Quinn director Kevin Lunney last month.
Mr Lunney was abducted near his home in Co Fermanagh and attacked.
The directors were told they had not learned their lessons after what happened to Mr Lunney.
It also threatened Cavan County Council staff or other contractors who remove posters erected as part of the campaign of intimidation against the directors.
It warned that they will be targeted if they remove the posters.
The five directors are Kevin Lunney, Tony Lunney, Liam McCaffrey, Dara O'Reilly and John McCartin.
One of the directors said the most recent death threat shows that the "faction" behind it are "emboldened and are undeterred from their specific agenda."
Speaking on RTÉ's Drivetime, Mr McCartin said he is "not minded to succumb to criminality."
The father-of-five said he must trust the trust the institutions of the State and he believes gardaí are "making every effort to ensure their safety".
Minister for Justice Charlie Flanagan described the threat as a "chilling and sinister development."
Speaking on RTÉ's Six One, he urged anyone with information to contact gardaí.
Mr Flanagan said those who come forward with information will have the protection of the State.
When contacted by RTÉ News this evening, Seán Quinn said he had heard nothing about this letter and would not be commenting.