19 September 2012 7:01am

The Australian Prudential Regulation Authority will not have to produce documents sought by plaintiffs in a class action relating to the timing and adequacy of disclosure by National Australia Bank.

The plaintiffs have already obtained many documents from NAB (and also from Ernst & Young, the bank's adviser) that relate to the analysis and decision making by the bank on the portfolio of credit default obligations that the bank wrote down in a minor way in early 2008, and then wrote down heavily later in the year.

Some of these documents tell NAB's side of its dealings with...