POLICE have come up with a new way of tracking down valuable and irreplaceable stonework stolen from across East Lancashire.

Crooks are stripping the Ribble Valley and Burnley countryside of ancient dry stone walls and taking stone ornaments and features from private homes and graveyards.

In some cases entire sections of walls have disappeared overnight to feed the black market demand for cheap stone.

Now police are spraying stone throughout the area with a liquid containing "forensic codes" that glow under ultraviolet light and reveal where it is from.

The liquid, called Smart Water, has been devised by a Newport company specialising in forensic crime prevention and is believed to be a world first. Stone theft from rural areas now accounts for 15 per cent of property theft in East Lancashire and is increasing by five per cent annually.

Police estimate that several thousands of pounds worth of stone is being stolen every year and ancient dry stone walls in particular are irreplaceable.

There have been 362 reported stone thefts in Burnley, Pendle and Rossendale, so far this year, with many more in Ribble Valley.

Ribble Valley crime prevention officer Peter Wareing said: "The theory is that each location will get a unique application of the liquid and our officers will be issued with ultraviolet keyrings. If they stop a van full of stone, they can detect if it's stolen, because it will glow under the light. They can then arrest the offenders. Furthermore, a simple test on the forensic code contained in the liquid sprayed on the stone will reveal where it is from, giving us the evidence we need to secure a prosecution. We will also be able to tell whether stone used in building work is stolen or not.

"This scheme is unique to East Lancashire, but if successful I understand it may be used elsewhere in county and it is likely we will eventually be talking to police forces throughout the country. It's an exciting development in our efforts to tackle rural stone theft."

Burnley police officer Simon Evans, who initiated the project, said: "A number of local organisations, including the National Trust, have benefited from this project in its pilot phase. This ground-breaking development shows just how determined we are to crack this crime."

Phil Cleary, chief executive of Smart Water, said the initiative was a major scientific development for the company.

"Smart Water has numerous inside applications, but this is the first time we have been approached to develop a product for widespread use outside and our scientific team has worked long and hard to develop a spray that can withstand the weather. This development is exclusive to Lancashire and our first joint activity with a police service."

Dr Ruth Henig, chairman of the Lancashire Police Authority, added: "This new scheme will allow us to take advantage of modern technology."