COPPER thieves stealing cabling from telecom lines are facing a new weapon which coats them in invisible paint.

Communications giant BT has become the latest firm to join the fight against scrap metal thieves who are costing them millions of pounds a year in replacements and customer care.

‘SmartWater’ technology tags thieves with a coded substance which can be linked directly to the scene of the crime.

Lancashire cash-in-transit firms use the technology to trace stolen notes to the exact van and delivery time.

The technology has lead to more than 1,000 convictions of thieves and robbers.

BT said Lancashire is one of the worst areas for scrap metal thefts.

British Transport Police and the county force have already launched their own crackdowns on railway cabling and lead thefts.

When thieves target the copper cables, they will now be coated in SmartWater and ‘traps’ will be in ‘hotspot’ areas spraying the invisible paint on clothes and skin, where it stays for 60 days.

Bernie Auguste, head of security for BT’s local network business Openreach, said: “Any criminal who targets the BT network in Lancashire now risks being ‘tagged’ with SmartWater, meaning that the police can trace them, and any stolen cable or equipment, back to the scene of the crime.

“Cable theft, which has been more prevalent in Lancashire than many other parts of the UK, affects not only us as a business, but all the people across the region, who rely on access to phones and broadband.

"With the help of this technology we’re fighting back.

“The support of the public is essential. People can help by being our eyes and ears and reporting anything suspicious to police.”

BT’s metal theft taskforce has been set up to capture persistent offenders.

Anyone arrested for metal theft will be examined for traces of SmartWater, as will their house and property.