The 66-year-old appeared at the Criminal Courts of Justice in relation to the murder of two Ulster Defence Regiment soldiers in 1972.
He was detained by Garda detectives on Monday in Donegal under a European Arrest Warrant as part of a joint operation with the PSNI.
Detective Garda Sergeant James Kirwan told the court that in response to his arrest, Mr Downey said: “I’d say it was the DUP made the decision, not the DPP.”
Sergeant Kirwan said Mr Downey has surrendered his passport and had fully co-operated with gardaí.
Mr Downey’s lawyers said he would be contesting the application to extradite him to the north.
Senior Counsel Garnet Orange said Mr Downey had medical conditions and had had a heart pacemaker fitted and was anxious to have an early date set for a bail hearing.
Ms Justice Aileen Donnelly said she would hear the full extradition application on 23 November.
His bail application will take place on Thursday at the Criminal Courts of Justice.
Lance Corporal Alfred Johnston, a father of 4, and Private James Eames, a father of 3, died when a device exploded in a car they were checking on the Irvinestown Road, Cherrymount, Enniskillen on August 25, 1972.
It is claimed Downey’s fingerprints were found on tape recovered from the scene of the blast.
In 2014 Downey stood trial for the 1982 Hyde Park bombings in which four soldiers were killed and a number of people were injured.
The trial collapsed because Downey had been mistakenly awarded an “on-the-run” letter by the UK Government which said he was not wanted by police.
He has always denied being involved in the Hyde Park attack.Tags: