Quinn, whose €4bn (£3.2bn) business empire collapsed after a disastrous investment in now-nationalised Anglo Irish Bank, is being pursued by the bank for debts of almost €3bn.
The Irish Banking Resolution Corporation (IBRC), created from the remains of Anglo, asked the High Court to declare Quinn in contempt for violating an order not to interfere with foreign property assets worth an estimated €500m.
“I find it impossible to accept his evidence that he had no hand in matters after April 2011 His evidence is not credible,” Justice Elizabeth Dunne told a packed courtroom in one of the most keenly anticipated judgments of Ireland’s financial crisis.
The judge will decide on sentencing after hearing arguments from both sides this coming Friday about what action should be taken but said it would be difficult to persuade her that there should not be a custodial element in the penalty.
If he is jailed, Quinn, 65, would become the first major player in Ireland’s economic collapse to be imprisoned.