By David Miller BBC News in North Yorkshire

The northern henge is covered with trees but others are clearly visible

Tarmac wants to extend its present operations close to Thornborough Henges near Ripon in North Yorkshire.

The firm says it is not seeking to quarry on the earthworks which form the three 5,000-year-old circles which may have been a ceremonial meeting place.

But the Friends of Thornborough say Tarmac still wants to quarry up to within half a mile of the henges.

Rob Moore from Tarmac said the company would not be seeking to include the land under the henges as part of a review of mineral operations in North Yorkshire being conducted by the county council.

"We have taken the decisions after listening to concerns expressed by local people, some of whom have mistakenly believed that the henges were under threat from the imminent local plan review and believed this allocation would be tantamount to permission to extract sand and gravel from beneath Thornborough Moor," he claimed.

The henges are in open countryside near the A1

"We have said time and time again, and repeat, that the henges, which are scheduled ancient monuments within a scheduled protection zone, are not threatened by quarrying."

Tarmac has had a quarry at nearby Nosterfield for 14 years.

It wants to extend the quarry's life moving to land at Ladybridge Farm, nearer the henges.

The Friends of Thornborugh say this risks damaging items which could provide clues about the reason the henges were built.

"Tarmac's apparent about-turn on Thornborugh Moor is merely a publicity ploy to give objectors the impression that the fight to save the setting of Thorborough Henges has been won," Mike Sanders from the Friends claimed.

"There is still nothing to prevent Tarmac, at a time of its own choosing, submitting an application to mine Thornborough Moor where there is twice as much sand and gravel as at Ladybridge Farm."

Earth banks

The henges are three earthworks built in a line running north-south for about a mile.

Each henge consists of circular earth banks and ditches which may have been covered with gypsum.

It is thought the late Neolithic henges could be part of a chain of ritual sites from Boroughbridge in the south to Catterick in the north.

Tarmac has called a public meeting for Wednesday evening at which it will provide details of its proposals for Ladybridge Farm.

These proposals, it says, have been revised following feedback from local residents.