A water company has come up with an innovative way of deterring metal thieves following a spate of thefts across the country.
Soaring prices for copper, lead and bronze have seen everything from railway lines, phone lines and even war memorials targeted by thieves. The thefts are estimated to cost the economy around £700 million a year.
Thames Water has come up with a way of deterring the thieves, by using a chemically coded substance to invisibly brand metals on its sites.
Bob Collington, Thames Water's director of asset management, said: "Metal theft at our sites costs our customers millions of pounds to put right".
The firm said earthing cables and lead roofs have been ripped out at its water and sewage works, with Aylesbury, Marlow, East Hyde and Bishop's Stortford its worst-hit sites.
The special substance, Smart Water, marks metals with a tag only visible under ultra-violet light allowing metal dealers to identify stolen scrap metal - and the police to trace the culprits.
A Thames Water spokesman said: "Regular scrap yard checks will also be carried out across the Thames Water region and an increasing number of scrap metal dealers are also equipping themselves with ultraviolet lights making it very difficult for criminals to sell metal on."
He added that the firm was also working with local police and security specialists to install covert traps to capture criminals in the act.
Metal thefts have wreaked havoc on the railway network - more than £13 million worth of metal has been stolen from the railways within the last three years, according to British Transport Police (BTP).
The BTP figures published yesterday also showed that there were more than 6,000 incidents of metal theft between April 2008 and October this year.
Half of the incidents saw the loss of vital equipment required to ensure the safe and efficient running of the railways.
The biggest single haul - totalling about £600,000 - went missing six months ago.
Also in December Scotland Yard launched a dedicated unit, the Waste and Metal Theft Taskforce, to tackle the growing problem.
The team includes experts from BT and the local authority's environmental crime unit, and the taskforce will also advise other boroughs, particularly areas with high numbers of scrap metal yards.