EXPERTS are warning the oldest settlement ever found near Stonehenge could be destroyed by controversial plans to dig a tunnel under the ancient site.

Archaeologists say the proposed 1.8-mile tunnel could run less than 20 metres from the “ground-breaking” and "unparalleled" find at Blick Mead and "possibly obliterate other hidden secrets".

They say the discovery this month of a Stone Age "eco home" raises questions over the belief that Mesolithic families were purely nomadic.

Experts believe prehistoric man built a house around the giant, nine-metre-round root base of a large fallen tree.

The earthy, wooden wall and the three-metre-wide pit where the tree stood were lined with cobbles.

It may have had an animal-skin roof and the team found a stone hearth nearby.

And archaeologists believe large stones near the wall may have been primitive storage heaters – warmed by a fire and placed close to where people slept instead of keeping a fire burning all night.

Archaeological evidence suggests people lived at Blick Mead, a mile from Stonehenge, continuously for at least 3,300 years from 7596 BC to 4246 BC — when Britain first became an island.

And experts believe they may have been the forefathers of the builders of Stonehenge.

Evidence that people ate salmon, trout, hazelnuts and cooked aurochs — an extinct species of huge, wild ox — has been found.

The University of Buckingham's David Jacques, who has been co-ordinating digs at the site for a decade, said: “This is a key site for where Britain began.

"These people are adapting to nature in a really sophisticated and intuitive way, in contrast to our government in the 21st century who are expecting nature and our history to adapt to our needs to build a tunnel through this precious countryside."

Blick Mead was likely to have been chosen because of the presence of a constant temperature spring at a time when Britain was thawing after the ice age.

Useful plants grew nearby and the River Avon would have been a key transport route.

Andy Rhind-Tutt, chairman of the Amesbury Museum and Heritage Trust, said: "I sincerely hope that the team delivering the long awaited the A303 improvement look seriously at an alternative alignment that comes south of Salisbury and actually deals with all our traffic issues and away from this unequalled archaeological landscape. A plan has been put forward to Highways England to consider.

"It would be criminal to destroy such a rich heritage and connection with our ancestors for the sake of blocking the view to the passing public of Stonehenge.”

Highways England is believed to be investigating the archaeology where the proposed A303 tunnel would run over the coming months.

But Historic England, the National Trust and English Heritage welcomed the A303 tunnel.

Jointly, they said it could bring environmental, cultural and economic benefits.

They expect full, detailed environmental and heritage impact assessments to be carried out, and say Blick Mead’s importance would be taken into account.

Phil McMahon, inspector of ancient monuments for Historic England in the South West said: "We understand that any tunnel scheme is likely to be well away from the Blick Mead site.

"We will be keen to see that Highways England take full account of the Blick Mead site in developing and assessing a road improvement scheme, in addition to the very rich historic landscape of the Stonehenge World Heritage Site."

Ian Wilson, National Trust assistant director of operations for Dorset and Wiltshire said: "The landscape around Stonehenge is one of the richest in Europe and we would expect the importance of all archaeology to be taken into account."