The security of directors and employees of Quinn Industrial Holdings (QIH) is “treated with the utmost seriousness”, the Taoiseach Leo Varadkar has said.
One of the directors of the County Fermanagh company, Kevin Lunney, was abducted and tortured on 17 September.
He was dumped on a road in County Cavan, Republic of Ireland, 22 miles (35km) from where he was abducted.
Mr Varadkar, the Irish prime minister, met the five company directors on Sunday, to assure them of his support.
Mr Varadkar said he wanted to thank them for their courage, determination and their commitment to the company.
He met the directors after attending a ceremony in Enniskillen for Remembrance Day.
“I wanted to hear their views and assure them of the government’s support for QIH, which employs more than 800 people in Ireland and Northern Ireland, and is an integral part of the community,” he said.
“In particular, I wanted to thank Kevin Lunney for the resilience he has shown following his barbaric abduction, assault and torture.”
Mr Varadkar said he discussed his recent meeting with the Garda (Irish police) commissioner, Drew Harris, and the Irish minister for justice, Charlie Flanagan.
“I assured them that their own security, that of their employees, and law and order in the border region is treated with the utmost seriousness at the top of government,” said Mr Varadkar.
“Law and order must, and will, prevail in all parts of the country. We agreed to stay in contact as the criminal investigation against the perpetrators proceeds.”
Mr Lunney, a father of six, had his leg broken, was slashed with a knife and doused with bleach in a two-and-a-half hour ordeal.
The 50-year-old had the letters QIH cut into his chest with a knife and told the BBC’s Spotlight last week that he feared that he would never see his wife and children again.
After Sunday’s meeting, QIH issued a statement saying it welcomed the “personal interest” taken by Mr Varadkar “in bringing to justice those responsible for a campaign of terror and intimidation against its staff”.
“The company believes the establishment of a joint investigative team is a critical step and is satisfied that the necessary resources and resolve are now in place for an effective investigation,” it said.
The main suspect in the investigation into Mr Lunney’s attack died on Friday during a police raid in England.
Cyril McGuinness, 54, is thought to have suffered a heart attack as police searched his Derbyshire home.
That search was part of a joint police operation across the UK and Ireland in which almost 20 properties were raided.
The PSNI has said it would “continue to work closely” with the Garda Síochána (Irish police) and Derbyshire Constabulary to try to “bring the perpetrators to justice”.
Irish justice minister Charlie Flanagan said there were already 1,500 police in the border region – including three police armed support units.
“I am pleased that 150 additional officers have been assigned to the region in the last two years following a difficult period for policing arising from the 2010 closure of Templemore College,” he said.
The companies comprising QIH were formerly owned by Sean Quinn, who was once Ireland’s richest man.
When his business empire collapsed, businessmen, including his former associates, bought the companies.
Mr Lunney, who worked with Mr Quinn for many years and remained loyal after the County Fermanagh tycoon’s bankruptcy, was reinstated as a director and Mr Quinn was employed as a consultant.
Mr Quinn left that role in 2016, later saying he was forced out and his family had been “stabbed in the back”.
He has repeatedly condemned attacks on property belonging to the owners of his former businesses.