Public concern over environmental concerns has meant slower-than-expected progress in establishing Britain’s shale gas industry through so-called fracking, the National Audit Office spending watchdog said Wednesday.

“Progress to establish the commercial viability of extracting shale gas has been slower than government expected,” the NAO said in a report. In fracking, or hydraulic fracturing, water and chemicals are used to blast apart rock formations.

“Government attributes this slow progress in part to low public acceptance,” it said. Operators blamed the UK regulatory process which they said was in some ways “more stringent” than in other countries.

The British public’s opposition to shale gas had risen to 40 percent from 21 percent since 2013, said the NAO.

“Public concern has centred on the risks to the environment and public health, from fracking-induced earthquakes, and the adequacy of the environmental regulations in place,” it added.

So while the Cabinet Office had expected up to 20 fracked wells by the middle of next year, there had been only three.

One year ago, energy company Cuadrilla extracted shale gas in Britain for the first time since resuming fracking operations it had halted in 2011 over environmental concerns.

The British firm has borne the brunt of protests for trying to test whether fracking can unlock natural gas deposits in Britain.