An environmental group claims the Ministry of Economic Development misled it during mediation in the Environment Court over mining on Coromandel Peninsula.
The Coromandel Watchdog was involved in the hearings earlier this year. It says it would never have agreed to forgo a mining ban in the District Plan if it had known statutory protections were under review.
The group says the Ministry of Economic Development should have disclosed during mediation that schedule 4 of the Crown Minerals Act was under review.
The clause protects land with high conservation values.
The ministry says it acted in good faith and any decision to review schedule 4 was for ministers to make.