BT Openreach has introduced a new forensic technology to tag cable thieves and save on the "millions" it said it loses each year due to copper theft.
The telecoms company is starting a national trial of the forensic SmartWater technology from Monday, extending a pilot project already started in North London, it announced.
"We are accelerating the programme and the national roll-out will be completed by the end of the year," BT said.
SmartWater is an invisible liquid that can be made unique to a specific location. If thieves steal metal from BT cables, the traces of SmartWater will indicate both that an individual has been involved in a theft and also where the incident took place.
The marking liquid will be used to coat the inner core and outer shell of BT's copper cable, as well as used on general equipment at cable sites. In addition, some Openreach locations will have traps that spray intruders with SmartWater.
SmartWater contains a "forensic fingerprint" and "if it gets on the sleeves or hands, then it can be traced back to a specific location," a spokesman for BT said.
Cable thefts cost the communications giant "single digit millions" of pounds each year, BT said. In 2009, thefts of metal from the BT network grew by 9 per cent.
Last year, BT worked with police to arrest over 200 thieves. At the time, SmartWater had not been introduced, but BT Openreach had increased security with more patrols of sites, perimeter security and police collaboration. So far in 2010, 150 thieves have been arrested due to these measures, the BT spokesman told ZDNet UK.
No statistics have come back from the London trial of SmartWater yet, so conviction rates for that are unknown.
In April, BT phone and broadband services to around 1,400 customers in Kent were disrupted after copper cabling was stolen.
"Cable theft affects not only us as a business, but the millions of people who rely on access to phones and broadband across the UK, and with the help of this technology we're fighting back," Bernie Auguste, Openreach's head of security, said in a BT statement.