NATIONAL park chiefs have welcomed government plans to prevent fracking within their boundaries - except in "exceptional circumstances".

But the opening of the latest bidding process for companies seeking licences to explore for shale gas could lead to the controversial operation occurring elsewhere in the region.

Ministers have unveiled new guidance which means applications for shale gas developments in national parks, areas of outstanding natural beauty, world heritage sites and the Broads should be refused other than in "exceptional circumstances and in the public interest".

The Department of Energy and Climate Change said where an application in these areas is refused and the developer launches an appeal, Communities Secretary Eric Pickles would consider whether to make the final decision himself to ensure the policy is being properly applied.

A British Geological Survey revealed the potential for huge shale gas deposits under rural areas of North Yorkshire, County Durham and Northumberland.

Welcoming the new guidance, Chris France, director of planning at the North York Moors National Park Authority, said: "Any planning application for extracting gas by this or conventional methods would be considered carefully and judged against relevant planning policies which include a presumption against major developments in national parks except in exceptional circumstances.

"We particularly welcome the government’s acknowledgement that fracking would fall within this category.”

Yorkshire Dales National Park Authority chief executive David Butterworth said he did not believe there were significant shale gas reserves under the national park and the authority had not had any inquiries from any companies about exploration.

However, he added: "Of course, some national parks and areas of outstanding natural beauty are potentially affected by developments of this kind so we welcome the Government’s renewed commitment to the existing protections that are set out in the national planning framework.”

Outlining the new policies, business and energy minister Matthew Hancock said that unlocking shale gas had the potential to provide Britain with greater energy security, jobs and growth.

He added: "We must act carefully, minimising risks, to explore how much of our large resource can be recovered to give the UK a new home-grown source of energy.

"As one of the cleanest fossil fuels, shale gas can be a key part of the UK's answer to climate change and a bridge to a much greener future."

The licences which can now be applied for provide the first step to start drilling but do not give an absolute agreement to drill.

Planning permission, permits from the Environment Agency and agreement from the Health and Safety Executive will be required for further drilling.