The former billionaire Sean Quinn is seeking a report by Anglo Irish Bank that suggests the purpose of the colossal loans to the Quinn Group was to support his stake in the bank.
The report, a review of the Quinn Group loans, was prepared for the chairman of the bank, Donal O'Connor.
An early draft of the report said the Quinn loans were to "meet margin calls", but later drafts described the loans as working capital.
The so-called O'Connor report emerged during a separate court case in the Republic which the Anglo Irish Bank is taking against its former head of lending Tom Browne for outstanding loans of €50m (£41.2m).
Anglo, now known as Irish Bank Resolution Corporation (IBRC), is engaged in a massive legal battle with Quinn and his family to recover loans of €2.8bn (£2.3bn).
The purpose of the loans goes to the heart of the Quinn's case.
Anglo said the loans were working capital paid to Quinn companies and to family members.
The Quinn family claimed the loans were advanced illegally, when the share price was falling, to help him fund his losses as the bank's share price collapsed.
The Quinn family won a legal action in March allowing them to accuse the bank of market abuse.
The IBRC is to appeal the Commercial Court's ruling tomorrow.
The bank is also asking the Quinn family to stump up the cost - estimated to be more than €1m (£825,00) - of producing the huge swathe of documents that the family sought from the bank under discovery orders.
The battle is being waged on several fronts.
The Quinns have been accused of conspiring to put their assets beyond the reach of the bank, to avoid repaying some €500m (£412m) held in overseas assets.
The Sunday Independent reported recently that the fallen tycoon is believed to be trawling banks, accountancy firms and state bodies, asking them to disclose what they have about his business dealings on file.
Mr Browne obtained the O'Connor report under discovery in January this year.