Five South Australian political figures have failed to reach a legal settlement over defamation cases stemming from fake documents used by the Opposition in State Parliament.

Former opposition leader Martin Hamilton-Smith is being sued by four Labor figures over public comments he made about scientology relying on information from the documents.

The parties include Government Minister Tom Koutsantonis and former Labor senator Nick Bolkus.

They have failed to reach a resolution after almost an hour of confidential negotiations in the SA Supreme Court.

The case is a step closer to trial, with a directions hearing listed for next month.