Roderick Newall, 27, confessed to his father's twin brother Steven and his wife Gaye at the Dunkeld House Hotel, Perthshire, on 14 July, John Blackburn Gittings, Gibraltar's Attorney General, said.
'During a three- to four-hour conversation with Steven Newall and Aunty Gaye, he made statements amounting to an admission that he had killed his mother and father,' Mr Blackburn Gittings told the Gibraltar court.
Mr Newall denies the allegation. He was remanded in custody for a week after his application for bail was refused.
A former officer in the Royal Green Jackets, he was arrested at sea last month off Casablanca, north Africa after his yacht was intercepted by a Royal Navy frigate.
He is fighting extradition to Jersey, where police want to question him about the murder of his wealthy parents, Nicholas and Elizabeth, who disappeared from their home in October 1987.
Mr Blackburn Gittings told the court Mr Newall was a 'dangerous man' and would abscond if released. His aunt and uncle may also be in danger.
He said when Mr Newall was arrested he told police he had considered making a break for it and calculated on being hit by four bullets before being able to grab a rifle. 'It was a strange thing to say in that situation,' Mr Blackburn Gittings said. 'He is trained in anti-surveillance and weaponry. He is a dangerous man.'
Judge Felix Pizzarello ruled against the bail application, saying he would consider again when he had all the evidence before him.Reuse content