Cornish hedges believed to be more than 4,000 years old are under threat from developers, say conservationists, as regulations fail to protect them from being destroyed.

Almost 100 miles of precious hedges have already vanished and the Cornwall Wildlife Trust has warned that more could be removed to make room for housing and industrial estates.

Brimming with flora and fauna, Cornish hedges are important wildlife corridors for hedgehogs, adders, harvest mice and bats. Some are thought to be more than 4,000 years old - making them among the oldest human-built structures in the UK.

Under the Hedgerows Regulations 1997, it is illegal to remove most countryside hedges in England and Wales without the local council's permission.

But because Cornish hedges are typically made from earth and stone, and have trees or bushes growing out of the top, they do not always have this legal protection.

Cornwall council's website states: “Cornish hedges in their great variety do not always meet this definition."

It advises landowners to check with the council's planning service if they are considering removing a hedge.

Cornwall council is now calling on the government to help save one of the most beloved features of the landscape in south-west Britain.

The council says it is "committed to protecting them as part of our unique and distinctive environment and heritage" and it would like the freedom to “develop and utilise an alternative system for the protection of Cornish hedges”.