Government officials have reassured people in Bath that they are "fully aware" of the real fears in the city over the impact of fracking on its world-famous hot springs.
Civic leaders in Bath are determined to keep up the pressure on ministers to declare the region around the city a frack-free zone because of fears that the deep drilling for gas could disrupt the historic water flow.
So far the only interest from energy firms has been in exploration for coal bed methane - a gas which lies significantly above the rocks which contain the source of the hot springs flowing into the Roman Baths and Thermae Bath Spa.
But Bath and North East Somerset Council and city MP Don Foster are worried that companies will want to drill down the two miles-plus to get at the potentially lucrative shale gas under the Mendips.
They are concerned not just about the impact on the city's tourism jewels but also over the possible knock-on effect on the structure of buildings because of the drying-out of the ground.
The Department of Energy and Climate Change, which licenses the exploration and extraction process, says it understands the worries.
It said: "DECC officials have visited Bath and been briefed on the issues by B&NES. We are fully aware of the unique situation, of the World Heritage Site status of the Roman Baths, and of the historical and economic importance of the hot springs to Bath.
"However, there are no current proposals for fracking in the area, and if any such activities were proposed, they would require planning permission. B&NES would be able to object (if the location is outside its area) or take account of the issues directly if within its area.
"There are proposals for conventional exploration activities in the region, but these do not involve fracking."
Fracking would see blasting of the underground geology to release trapped energy and has been hailed by its supporters as a possible solution to the country's energy crisis.
But the council and Mr Foster say any such technology would be gambling with the sensitive - and still largely unknown - pathways followed by the water which supplies the baths and spa.
Mr Foster, who is now a minister in the Department of Communities and Local Government, said: "While fracking may, in some circumstances, be worth pursuing under carefully controlled conditions, it would be inappropriate anywhere near Bath, with so many uncertainties about its possible impact on the water courses. Any interruption or displacement of the water supplies would not only damage our vital tourism industry but also the hydrostatic pressure which holds up the city centre. Unless all the uncertainty is removed, we need to ensure no fracking is allowed.
"I have met with a leading expert on fracking and he was unable to allay my concerns. I have also met with senior council officers to discuss the issue and know that they have similar concerns. I have, therefore, written to the Secretary of State urging him to ensure we are protected from any immediate fracking and have had meetings with him to reiterate the point."
Council leader Councillor Paul Crossley (Lib Dem, Southdown) said it was important to understand that fracking involved processes going far deeper than the mining which characterised north east Somerset until the last pit shut 40 years ago.
He said: "The council's position is that the risk in B&NES is so great that it is not worth considering. We manage a World Heritage Site for the world."
He added that the risk of Bath effectively drying out could also cause a "disaster" for building structures.
The council is keen to extend the existing County of Avon Act, which gives it a veto over drilling work which could affect the hot springs, but which only covers the city itself. But such legislative change would be virtually unprecedented.
B&NES has even considered buying all the exploration licences itself.
At the moment, firms have expressed interest in test drilling for coal bed methane in Keynsham, Compton Martin and Ston Easton.
