The Supreme Court has heard that a computer hard drive from a Quinn Group Russian company from which crucial new evidence was retrieved had been deliberately smashed.
Lawyers for IBRC said the files showed employment contracts which had been created to allow for multi-million termination payments to members of the Quinn family.
It has also emerged that the contracts provided for huge payments in the event of injury “or an assassination attempt” while on official company business.
Senior Counsel Paul Gallagher said the existence of such contracts had previously been denied by the Quinns.
Mr Gallagher said an administrator appointed by the bank uncovered the hard drive and believed it had been deliberately smashed.
One of the contracts linked Seán Quinn Jnr to a company at a time when he said he had no involvement with it.
It provided for a payment of €7.4 million should his employment be terminated for any reason.
Mr Gallagher said Seán Quinn was in control of a company which he told the High Court he had no control over and from which he could not retrieve any money or information.
However, emails retrieved from the computer show Seán Quinn Jnr issuing instructions that bank transfers must be authorised by him alone.
Mr Gallagher said it was only for the fact that the bank had the "good fortune "to appoint a receiver over the company in August that it was able to uncover the information.
Otherwise the Supreme Court would have had to deal with this appeal on the basis of false information, which is what the High Court had to do earlier this year.
The Supreme Court is sitting for a third day to hear an appeal by Seán Quinn Jnr against a three-month jail term imposed for contempt of court.
He was also jailed for failing to take steps to reverse an asset-stripping conspiracy aimed at moving money beyond the reach of the former Anglo Irish Bank.