FINANCIER Derek Quinlan has claimed Paddy McKillen's relationship with the Irish Bank Resolution Corporation (IBRC) does not represent "normal banking practice".
Mr McKillen owes the bank -- once known as Anglo Irish -- €300m, while the companies he is connected to owe an additional €1bn.
In a closing statement to the High Court in the on-going case between Mr McKillen and the Barclay brothers, Mr Quinlan said that the Belfast-born businessman was a "borrower in default".
"Despite his protestations to the contrary, Mr McKillen's financial position with IBRC does not represent normal banking practice," the statement prepared by Mr Quinlan's lawyers said.
"He is a borrower in default of his very substantial payment obligations, who has yet to reschedule his debts or provide his creditors with a statement of his net worth, despite their repeated requests."
Concerns have been raised about the relationship between Mr McKillen and IBRC chief executive Mike Aynsley.
Mr McKillen has taken a case against David and Frederick Barclay over their attempts to take over Coroin, the company which owns Claridges, the Connaught and the Berkeley hotels in London.
During the case, it has emerged that Mr Aynsley sent Mr McKillen text messages to tell him the bank had decided to work with him rather than deal with the Barclay brothers over his debt.
Mr Aynsley warned Mr McKillen against making this information public.
Mr McKillen has said he enjoyed a good relationship with the bank and had a deal to pay back borrowings over the next five years.
However, Mr Quinlan -- whose sale of shares to the Barclays is at the centre of the case -- said Mr McKillen was unable to pay his debts when they were due.
Mr McKillen is claiming Mr Quinlan's 35pc stake should have been offered to him under a clause in the shareholders' agreement of the company. The share was sold to the Barclays by NAMA.
"Instead, he seems to regard the repayment of the debt as a matter of negotiation to be conducted after the dates for repayment have expired," Mr Quinlan's statement said.
"As with many of Mr McKillen's dealings with IBRC, and his financial matters generally, this is an odd state of affairs. His position in this context is wholly implausible."
Meanwhile, NAMA, in its closing statement, said Mr McKillen had been told repeatedly before the shares were sold to the Barclays that its objective was to get full repayment as soon as possible.
"Any dispute between Mr McKillen and the Barclay interests as to how and why Coroin came to find itself in this situation is irrelevant," the statement said.
"The reality was that, having been offered payment in full for the Coroin loans, there was nothing that Coroin could have said which might have changed NAMA's mind."