SNP MP warns of fracking threat to Scotland's "clean, green" food and drink industry

Winemakers in France and California and brewers in Germany have also opposed fracking in case it pollutes their water supply and damages their reputation.

In August, SNP ministers banned genetically modified crops in order to protect the “clean, green status” of Scotland’s food and drink industry.

Drawing a parallel, McNally told the Sunday Herald: “I’m not dead against it [fracking], but I don’t think we need to take this stuff out of the ground yet. We’ve got a huge food and drink industry in Scotland. We’ve got to protect the purity of our water.

“It’s fixed, so why would you want to break it? We have to be very cautious. All it would take is one leak for people to shy away from buying water products and the crops we produce.”

The Falkirk MP added: “Whisky is growing at a rate of knots. We shouldn’t want to jeopardise it in any way.

“If we’ve got this clean and green image, then we should protect it at all costs.

“There’s a lot of people put their life into producing crops and drinks, whether that’s Irn Bru or whisky or sparkling water. There are so many things dependent on the quality of our water.”

Hydraulic fracturing, or fracking, works by pumping a mixture of chemicals deep underground at high pressure in order to release methane gas trapped in shale rocks.

The technology has transformed the energy market in America, but critics warn it is a pollution threat to the water table and burning the gas contributes to global warming.

Shale beds across Scotland’s central belt contain an estimated 80 trillion cubic feet of gas.

SNP ministers announced a moratorium on fracking earlier this year, pending further research.

However Ineos, which runs Grangemouth refinery, are currently holding public meetings to promote the potential for fracking in Scotland.

The company has paid the SNP thousands of pounds for exhibition space at this month’s conference in Aberdeen to lobby party members, and will meet SNP MPs at Westminster at the end of the month.

Despite the SNP using the “Frack Off” slogan in the general election, its refusal to ban fracking has led to growing suspicions that ministers plans to allow it after the Holyrood election.

Energy minister Fergus Ewing has also refused to prohibit other “unconventional gas” methods, such as burning undersea coalbeds, while Finance Secretary John Swinney has called for the potentially lucrative taxes from fracking to be devolved to Holyrood.

Party insiders say tensions between grassroots members demanding a ban and the SNP leadership are now as bad as those over Nato membership before the 2012 conference.

Although numerous SNP branches submitted motions calling for a ban on fracking, not one was accepted by party chiefs.

One well-placed SNP source said there was a “huge feeling of disillusionment” among activists, adding: “If headquarters don't back members half the party stand to walk away”.

Another told the Sunday Herald: “This issue has more traction in the party than indyref2. People in [fracking hotspots] know they’ll be crucified if this goes ahead. It’s a really big issue. People think the leadership have made up their minds. We’re going to lose members over it.”

The SNP Trade Union Group, whose 16,000 activists represent around one in seven of the SNP membership, also plans to call for a ban at the conference.

Last year, Alex Salmond warned against fracking in case it contaminated the water supply.

Asked if it should be part of Scotland’s energy mix, the then First Minister said: “Not onshore. I don’t think that’s a good idea in a relatively unpopulated area. But in a densely populated area you’ve got to be able to answer the water table situation.”

A government spokesman said ministers would take an evidence-led approach to fracking, with a moratorium in place and the details of a public consultation to be announced shortly.