The mine's main works would be close to the final stages of the Coast to Coast Walk

Campaigners battling against the setting up of a huge mine in a national park say the fight is not over, despite formal approval being granted today.

The Campaign for National Parks said the story isn’t over yet for its opposition to the York Potash plans.

The application to extract billions of tonnes of minerals from the North York Moors national park is the biggest ever received by a UK national park.

Authority members voted to accept the proposals in June, but the charity said it will scrutinise the mass of documents for the plans. York Potash hopes to extract polyhalite and other minerals used in fertilisers, much of which it plans to export. It will also construct a 36.5km (23-mile) tunnel to Teesside from where the minerals can be exported.

The formal approval notice was published today by the authority, along with more than 1,300 documents relevant to the proposal.

A Campaign for National Parks spokesperson said: “The issuing of the formal decision notice for the York Potash planning application is another key step for this project but it is still not the end of the story as far as we are concerned.

“We remain convinced that the project is completely incompatible with national park purposes and that the promised economic benefits for the surrounding area do not justify the huge damage to the national park’s landscape, wildlife and local tourism economy.”

Many local residents and bodies support the York Potash plans because of the economic boost they hope the mine would bring.

“Now that the formal decision notice has been issued, details of final planning conditions and the S106 agreement are in the public domain, and we will be reviewing these and other relevant documentation to determine whether we have grounds for a legal challenge,” the CNP spokesperson said.

“This is a major undertaking for a small charity but it is something we feel we must consider given the significance of this decision for the protection of all our national parks.

“We have six weeks from the date of the decision notice to apply for a legal challenge.”

York Potash, which is owned by Sirius Minerals, estimates that the new potash mine could create up to 1,000 jobs and would also bring revenue benefits at a national level.

It said resources to compensate for the harmful impacts of the development will be paid by the company more than 100 years. The park authority said funding will be used for a variety of projects including tree planting and increased promotion of the wider North York Moors to potential visitors.