Three judges working on a major drugs and money laundering case have been replaced because they were unwittingly given access to French state secrets in one of the trial documents, broadcaster NOS said at the weekend.

The information in one of the pieces of evidence should have been blacked out but had been left untouched, NOS said. The file the broadcaster said, may have been about the recent police hack of secret message service EncroChat.

The case centres on 49-year-old Rotterdammer Roger P, also known as Piet Costa, a suspected cocaine baron who is said to be responsible for the torture chambers found in Noord Brabant last year.

The mistake came to light on July 16 when a member of the public prosecution department team sent a censored version of the document to the judges, explaining why some parts had been blacked out.

One of the judges then realized that she had read an uncensored version of the same document several months earlier.

That meant the judges had more knowledge about the case than both the public prosecution department and the defence, NOS said. Because the information is secret, it cannot be passed on to them.

The only option, the judges said, is to stand down and start the case again with a new bench.