Séan Quinn urged to speak out over 'escalating violence' at former businesses
US investment funds that bought some of Séan Quinn's firms have urged him to condemn "escalating violence and intimidation" directed at the firms.
The funds have also accused Mr Quinn of trying to "drive a wedge" into the management team running the businesses.
The comments are from an email obtained by the Impartial Reporter and seen by the BBC.
Mr Quinn responded that both he and his family "condemned and will continue to condemn all negative activity".
The former billionaire businessman, from County Fermanagh, lost control of his manufacturing businesses in 2011 following a disastrous bet on shares in Anglo Irish Bank.
The consortium of banks and other lenders that took over the group gradually sold off its various divisions.
The packaging and construction materials business, based in Counties Cavan and Fermanagh, was sold to Quinn Industrial Holdings.
It is run by some of Mr Quinn's close associates but is jointly owned by three funds - Brigade Capital, Contrarian Capital and Silver Point Capital.
Mr Quinn is a consultant for Quinn Industrial Holdings and is the highest paid person at the company.
In the email the investor group said "threats...false personal attacks and vandalism" were adversely impacting on its "willingness to continue to invest and grow".
They called on Mr Quinn to take an "active approach" against the "increasingly negative activity in the community".
The email added that the funds have no plan to sell the firms to Mr Quinn.
The investor group also said that Mr Quinn needed to "rectify his relationship with our senior management team".
In a statement, Quinn Industrial Holdings said that Mr Quinn has his own advisor who is in "direct discussions with the investors in relation to his role within the business".
"Any decision related to the outcome of those discussions is exclusively a matter for the US investors," it said.
After previous attacks on former Quinn businesses, Mr Quinn said he condemned unlawful acts and that anybody carrying out such acts were not acting in his name.
A statement from the Quinn family on Friday said: "Séan Quinn and the Quinn family's stated position is that they have always condemned and will continue to condemn all negative activity in the local area.
"Séan has a good working relationship with the US investor group and all discussions between those parties are private and confidential.
"Séan has no comment to make on the management team, save to say that he has drawn the US investor group's attention to matters that he believes need to be addressed to protect the Quinn Group and the jobs that it provides to the local community."