Businessman Jim Kennedy has been taken to hospital after being arrested for questioning about bribery and corruption allegations.
The 63-year-old is understood to have complained about chest pains in the early hours of the morning while being detained at Irishtown garda station in Dublin.
He was taken to St Vincent's University Hospital at Elm Park at around 4am on Wednesday, where he was undergoing tests.
Fraud detectives have suspended his arrest period and will resume questioning Mr Kennedy when he is released from hospital.
Mr Kennedy was arrested on Tuesday after he walked out of a High Court hearing on the 53 million euro hike in land prices at Carrickmines in south Dublin.
The developer had been wanted for questioning by the Criminal Assets Bureau (CAB) for the last seven years. He had been living in the Isle and Man and later in Gibraltar.
Gardai were quizzing him about alleged involvement with Jackson Way Properties, which owned 17 acres of land at Carrickmines that was rezoned for development in 1997.
The lands were frozen by the CAB in 2005.
At the time, then CAB chief Felix McKenna said it was believed corrupt payments to county councillors secured the rezoning from agricultural to industrial use.
Former government press secretary Frank Dunlop, who was jailed for 18 months after pleading guilty to corruption, was accused of brokering the deal.