Treasury Holdings says a decision by the National Asset Management Agency to appoint receivers to some of its assets is irrational, disproportionate and an unfair exercise of its powers.

The Commercial Court has begun hearing a challenge by Treasury to NAMA's decision to call in around €1 billion worth of loans and appoint receivers.

Treasury claims NAMA is displaying an uncommercial attitude to Treasury's assets - to the detriment of Treasury, NAMA and the public purse.

Treasury claims the entire group and 400 jobs - 300 of which are based in Ireland -are under threat. The property development company was founded in 1993 by Johnny Ronan and Richard Barrett. It has an interest in 130 properties in seven countries.

Senior Counsel Michael Cush, for Treasury, told the court Treasury was challenging NAMA's decision on December 8 2011 to call in Treasury's loans and its decision on January 25 of this year to appoint receivers.

He said one of the main grounds of Treasury's challenge was an allegation that there had been an absence of fair procedures and that Treasury had had a right to be heard in advance of the making of those decisions.

Mr Cush said it was undoubtedly the case that Treasury was "balance sheet insolvent" - its liabilities significantly exceeded the value of its assets. He said that was because of the extraordinary decline in the value of its Irish property assets.

He said NAMA had described Treasury as hopelessly and grossly insolvent. That was true if the demands for repayment were valid.

But he said Treasury had continued to operate and was in the process of negotiating continuing terms under which NAMA would provide ongoing facilities to the company when NAMA made a decision to call in the loans.

He said Treasury did not accept that it had made an agreement with NAMA which precluded it from taking this action.

Mr Cush said two international investors had signalled that they were willing to improve their offers for the Treasury loans. He said that Treasury was pursuing a strategy to allow it to exit NAMA.

Mr Cush also said that NAMA's decision in December last year to call in the loans was not communicated to Treasury until January 9. He said that a one-month period would have given more than sufficient time for Treasury to make representations to NAMA.

He said NAMA had been less than open and transparent with Treasury. He said there was correspondence between NAMA and Treasury during that month but at no time did NAMA say they had decided to call in the loans and appoint receivers.

The case is expected to take at least four days.