Gardaí investigating the abduction and torture of Quinn Industrial Holdings (QIH) executive Kevin Lunney have arrested a total of four men in Dublin and Cavan.

Two men, both aged 38, were arrested in Dublin on Thursday and were taken respectively to Ballymun and Finglas Garda stations for questioning.

They are being detained under Section 50 of the Criminal Justice Act, which is used for questioning suspected gang members and allows for the detention of suspects without charge for up to seven days.

They also said 66-year-old man was arrested in Co Cavan for an offence contrary to Section 72 Criminal Justice Act 2006 and is being detained under Section 50 at Monaghan Garda station.

Gardaí appealed to anyone with information “no matter how insignificant it appears, on this vicious criminal attack or any other criminal activities” that have taken place in the Cavan/Fermanagh area in recent years to contact them.

The latest arrests come a week after two men and a woman were detained in Co Cavan in connection with the incident. They were later released withouth charge.

Mr Lunney (50), a father of six, was abducted close to his home in Co Fermanagh on September 17th. His leg was broken and the letters QIH were carved into his chest during the 2½ hour ordeal before he was dumped on a roadside in Co Cavan. The attack represented an escalation in the campaign of intimidation and violence against the executive team at QIH.

Since 2011 people and companies involved in the sale, acquisition or management of assets formerly owned by businessman Seán Quinn have been targeted. Mr Quinn has condemned the violence and insisted those responsible were not acting in his name.