Public support for "fracking" continues to decline, despite promises of financial payments to communities who allow shale gas development, a survey has found.

Backing for the controversial technology, which involves pumping liquid at high pressure deep underground to fracture rock and release gas, has been on the slide since protests in Balcombe in the summer.

The latest in a series of surveys on public perceptions of the issue has shown that concerns over water pollution as a result of fracking have continued to increase.

Worries about water contamination had been declining before the Balcombe protests, but it formed a key issue for protesters worried that energy company Cuadrilla would frack in their area.

The survey of 3,751 people this month found that of those who had heard of fracking, 43% associated it with water contamination compared to 27% who did not.

In July, before the protests got going, 35% associated fracking with contaminating water, and 30% did not, a gap of just five percentage points.

But the split grew, with those concerned about contamination outstripping those who did not associate fracking with the issue by 11 percentage points in September, with the gap now standing at 16 percentage points.

Fewer people now consider shale gas to be a clean energy source either, with 30% thinking it was clean, compared to 43% who did not.

In July last year, 34% of people considered shale a clean energy source, while 37% did not, the research by the University of Nottingham found.

And although more people do see it as a cheap source of fuel, suggesting that Government claims that the alternative energy source could cut bills is having an effect, even that view is less strong than it was six months ago.

Half of those polled who had heard of fracking think shale is cheap, compared to 27% who do not.

Six months ago it was seen as cheap by 55% of people while just over a fifth (21%) did not think it was a cheap option.

Professor Sarah O'Hara, from the University's School of Geography, said the survey did show that people considered shale was a cheap form of fuel but the trend was moving away from a positive view of shale on cost.

"This suggests that the 'turn against fracking' indicated in September was not a 'blip' and may represent an increasing sense of unease with the environmental implications of fracking techniques amongst the UK public."

General support for fracking in the UK has also reduced and opposition has grown, although more than half still support it.

Friends of the Earth energy campaigner Tony Bosworth said: "With more communities facing up to the threat of fracking in their backyard it's little wonder that people increasingly realise that shale gas has been massively over-hyped, and its impacts down-played.

"Communities are right to be concerned about the impact that fracking will have on their lives and environment.

"And with experts warning that it won't lead to cheaper fuel bills or do much to tackle climate change, the Prime Minister's shale gas enthusiasm looks increasingly misjudged."