The Royal Commission on the Pike River coal mining tragedy says a leak of evidence before its delivery last week, led one other submitter to express reluctance at revealing his evidence in advance.
The Commission is looking into the explosions in the West Coast mine last November that killed 29 men on 19 November.
Evidence due to be presented next week from a Japanese mining engineer was made available last week and broadcast on Radio New Zealand.
Special counsel Simon Mount told the hearing on Monday that it was highly inappropriate for confidential submissions to be leaked.
He said it made it impossible for sections of a submission to be suppressed later if required, and the commission had been approached by another person with a request to withhold statements ahead of delivery.
Mr Mount says this defeated the transparency which was sought by publishing witnesses' reports on a secured website, before they were presented to the inquiry.
Earlier, Royal Commission head Justice Pankhurst told reporters he was perturbed and aggrieved by the leaks.