Four men arrested on Thursday in connect with the abduction and torture of Kevin Lunney were still in Garda custody on Friday night.
The men, aged from 22 to 66, were being detained in Monaghan and Dublin Garda stations under section 50 of the Criminal Justice Act, which allows for suspected gang members to be held for seven days.
One of those being held is the chief suspect for the abduction and torture of Mr Lunney, the chief operations officer at Quinn Industrial Holdings (QIH).
He was abducted on September 17th near his Co Fermanagh home and tortured before being dumped 2½ hours later in Co Cavan.
The other three, all arrested in Dublin, are suspected of sourcing vehicles for the attack or carrying out surveillance on Mr Lunney ahead of his abduction.
The arrests bring to seven the number of people detained to date over the attack on Mr Lunney.
The attack formed part of a campaign of violence and intimidation against QIH executives over the past five years.
