Welsh environment minister Carwyn Jones has told a national park it must change its planning blueprint to safeguard sand and gravel mining sites.
Park authorities in the Brecon Beacons say the ruling could have severe environmental implications.
Despite 1,000 residents of Talybont-on-Usk signing a petition against mining in the area, the Welsh Assembly Government (WAG) says the Brecon Beacons National Park Authority must protect the areas from being built upon in its local unitary development plan (UDP).
It has been told it cannot adopt the UDP in its present form, which means all the park’s planning policies are put into doubt. No viable deposits of sand and gravel have been identified in the area.
Chris Gledhill, chief executive for the Brecon Beacons National Park, said: “Although WAG is not asking the national park to allow sand and gravel to be dug up, it is asking for the resources to be protected against being built upon.
“If there was ever an application to open a quarry, the [authority] has very strong planning policies in the Local Plan and UDP to prevent this from happening.
“Not only do we recognise the impact it would have on our wildlife and landscape but we realise that such development in any area within the park could damage our tourism industry, which is vital to our economy.”
Carwyn Jones said: “I regret having to take action that intervenes with the adoption of any UDP, but I have to ensure that development plans implement national planning policy.”