Fresh doubts have been raised about the potential for fracking to provide new energy supplies.

Academic experts say claims that fracking in areas like Kent could deliver large supplies of gas were misplaced and had been over-hyped.

A study by Professor John Underhill from Heriot-Watt University singled out the Weald area of Kent as among locations where forecasts had been optimistic.

He said reservoirs of shale gas had been damaged by seismic activity 55 million years ago, causing some of the deposits to escape.

“Both sides of the hydraulic fracturing debate assume that the geology is a 'slam dunk' and it will work if exploration drilling goes ahead.

“The science shows that our country's geology is simply unsuitable for shale oil and gas production. The implication that because fracking works in the US, it must also work here is wrong.”

Areas like the Weald had “been highly deformed by folds and faults that cause the shales to be offset and broken up into compartments. This has created pathways that have allowed some of the oil and gas to escape.”

While there are currently no plans for fracking in Kent, energy companies have previously identified sites in east Kent as possible options.

However, three planning applications for test drilling in east Kent were made to the county council but then withdrawn.

A survey by the British Geographical Society examining the Weald basin concluded that while there was no significant shale gas potential there was potentially “a significant volume of shale oil.”

Rosemary Rechter, of East Kent Against Fracking, said: “The shape of our geology means we are in an area - particularly west Kent - where there are dips and bumps that make extraction difficult.”