The directors of Quinn Industrial Holdings have received another death threat.
It was delivered to The Irish News in Belfast on Monday night. It informs the five directors that it is their 'last warning'.
The Gardaí have spoken to each of them individually as part of their investigation.
It follows the abduction of Quinn director Kevin Lunney last month.
Mr Lunney was abducted from near his home in Co Fermanagh, attacked and later dumped at the side of the road in Co Cavan.
The 50-year-old executive was left with serious injuries to his legs, torso and face.
Police described the injuries he suffered as "life-changing."
John McCartin is a director of Quinn Industrial Holdings, and condemned the latest threat.
"From what we know a letter was delivered to a newspaper office and it warns that we have not learned our lessons from Kevin's abduction.
"It says that we have to resign immediately, as we were previously instructed to do.
"That we have broken commitments, and generally a warning that the final or the permanent solution will be enacted on us if we don't resign".
Fianna Fáil justice spokesperson Jim O'Callaghan has also condemned the threat.
He said: "This campaign of violence and threats against the directors of Quinn Industrial Holdings should not be tolerated, and anyone associated with these threats must feel the full force of the law.
"The attack on businessman Kevin Lunney last month was a vicious and cowardly attack on a man who was returning home from work. Nobody should be made to live in fear like this.
"It is important now for both the Gardaí and the PSNI to work together to bring those behind these threats, on members of Quinn Industrial Holdings, into custody.
"These attacks and threats must not and should not be tolerated, and I strongly urge anyone who may be protecting these thugs to come forward with information" he added.