There will be no changes to mineral royalty rates in this year's West Australian state budget, and questions are now being raised about cash already booked for the revenue source.

After a review of the state’s royalty system, mines and petroleum minister Bill Marmion said on Wednesday that 18 recommendations had been “noted” but none would be adopted in 2015/16. Opposition treasury spokesman Ben Wyatt then asked Treasurer Mike Nahan in parliament where $560 million in revenue booked in the…