Reopening Dean Quarry on the Lizard Peninsula could generate between £140 million and £190 million for the Cornish economy, according to a report published on behalf of quarrying company Shire Oak.

A report by accountants Milsted Langdon on behalf of Shire Oak, which has already taken steps towards reopening the quarry, states that the benefits to Cornwall of such a move would far outweigh any negative impact through potential losses to tourism and local trade.

However the report's author Kevin Butler has admitted that his paper deals with benefits to Cornwall as a whole, and not necessarily in Coverack and St Keverne, the two areas that would be most affected by renewed quarrying, and a local campaign group has said it does not take into account damage to the natural environment, particularly a local marine conservation area.

The report, prepared by consultant economist and former Bank of England agent Kevin Butler, predicts a net positive impact from the quarry’s operations of £160 million over 20 years of operation, or £190 million when inflation is included, or £120 million over a 15 year cycle, going up to £140 million with inflation.

The estimate includes an annual labour bill of £3 million, split between 50 permanent quarry jobs and payments for contractors, and £5 million spent every year on goods and services, plus £10 million in start up costs in the first year.

When estimating the benefit to Cornwall, Mr Butler's report has discounted 40 per cent of this operating

budget "because expenditure will be incurred outside the county."

Mr Butler said: “Dean Quarry is an important economic asset for Cornwall and has the potential to bring substantial economic benefits to the immediate locality and to the wider region.

“It would create new, well paid, non-seasonal jobs and the intention is that the majority of its operating budget would be spent locally, ideally within a 25-mile radius of the quarry. This would create a net positive impact valued at millions of pounds a year.”

Kurt Larson, managing director of Shire Oak Quarries, said: “Extractive industries remain a major part of Cornwall’s economy and Dean Quarry was worked for around 100 years before it was mothballed in 2008. This report shows the potential for the quarry to continue to make an important contribution to local employment and the economy."

Campaigners from Community Against Dean Superquarry (CADS), which is seeking a judicial review into plans for reopening the quarry, said the report is "out of date and flawed by inaccuracies and assumptions," and the group would be preparing its own socio-economic report.

The group said it ignores the fact the main contractor is Chinese firm China Harbour Engineering Company, and overlooks the value of tourism to the TR12 area worth £45millon each year, or nearly £1billion over a 20 year period.

A spokesperson said: "The report fails to mention the devastating environmental impacts of quarrying at the new proposed levels. CADS feel that one cannot put a direct economic value on nature and the unique and pristine environment of the Lizard Peninsula."

They added: "[Mr Butler] has missed that vital other ingredient in his economic analysis, that is defining accurately the existing and growing economy of the region, placing a value on it and then making the comparison

The clerk of St Keverne Parish Council said it was unable to comment at this time.