A POTASH firm hoping to build a £1.5bn mine in a national park says it has changed the way it will transport its product.

Sirius Minerals wants to extract up to 15 million tonnes of polyhalite every year under the North York Moors National Park, near Whitby.

Bosses previously revealed they wanted to move the polyhalite, a form of the fertiliser potash, through a pipeline system to port operations at Wilton, near Redcar, by digging a series of trenches.

However, the company, which has suffered delays to its planning application over its potential environmental impact, says it will now use underground tunnelling to substantially reduce any changes to the moors' surface.

It said the move will only take up 60 hectares, compared to 350 hectares needed for the original pipeline, using conveyor belts at depths of up to 360 metres.

The development, known as the York Potash Project, could create up 1,000 jobs.

Chris Fraser, Sirius Minerals' managing director and chief executive, said: “The system will use proven mining technology, minimising the impact at the surface and completely removing the need for any work in designated and protected habitats.”

Mr Fraser added the system will simplify the planning process, with the vast majority of the project determined by the North York Moors National Park Authority and Redcar and Cleveland Borough Council.

Bosses expect to submit the proposals by the end of July.