The debate will include loss of landscape versus economic benefits

It has been organised at Lee Moor by the Dartmoor Society, which says it is the first event of its kind in Devon.

Representatives from the china clay firms Imerys and Watts Blake Bearne will speak at the debate, and include economic benefits in their speeches.

Dartmoor National Park Authority's former director, Professor Ian Mercer, will make a case for the environment.

�18m is a considerable economic advantage to west Devon Ivor Bowditch, Imerys

People have been extracting china clay from the moor for more than 175 years. However, in recent years, some local residents have had concerns about expansion of the china clay works.

Professor Mercer said the debate will be weighing up whether the loss of landscape is worth the economic gain.

He said: "We will look at how does environmental pressure and technological difficulty mount a general pressure on whether you stay doing it or whether you go somewhere else."

Ivor Bowditch from Imerys said the companies would listen to all arguments and respond to any concerns.

He said he wanted to highlight the fact that china clay contributes about �18m to the local economy with its work around Lee Moor employing more than 200 people.

He also said the company's attitude to the environment was a modern one.

He said: "That �18m is a considerable economic advantage to west Devon.

"We know critics may say there is an ecological disadvantage, but we're trying to marry the two: the economic importance of the industry, but also to do that business in an economical and environmentally way which will allow the sustainability of the business."

The debate is being held at the Lee Moor Village Hall. It will be followed by a tour around nearby clay works.