The number of metal thefts in Hertfordshire had dropped over the last six months following a steep rise over the last few years, according to the county’s force.

Hertfordshire Constabulary said it had investigated 533 incidents in the first six months of this year compared to 773 over the same period last year.

The county has been blighted by an increase of thefts, which have seen overhead power lines and telecommunication cables targeted as the price of metals has risen in recent years.

Among the places affected over the last few years was the police’s county headquarters, in Welwyn Garden City, which suffered a communications blackout in February due to a cable theft.

The force said it did not believe any 999 calls were lost in the disruption, but a large reward was offered to help catch the culprits.

Over the last two years Hertfordshire Constabulary said it had ramped up its efforts against metal thieves.

Operation Devon was launched in 2010 in response to rising thefts of roofing lead, high voltage power cables, catalytic converters, which began as the price of metal started to rise.

In January 2012 a dedicated taskforce of six officers was formed to target metal thieves, particularly cross border criminals coming into Hertfordshire.

Officers said Hertfordshire companies and scrap dealers have also come under greater scrutiny to hinder thieves’ attempts to sell on their stolen wares.

More than 80 per cent of the county’s scrap dealers now require customers to provide proof of identity in the form of a photo driving licence, passport or national identity card.

DCI Liz Hanlon, who is leading Operation Devon, said: "Widespread and persistent metal thefts cause serious problems for people and businesses across the country, causing power cuts, damage to public buildings and disruptions to rail and telecommunications services.

"We are delighted that the number of metal theft offences appears to be on the decline and I think that the officers working on the Operation Devon taskforce and safer neighbourhood teams deserve credit for their hard work and professionalism.

"There have been fewer serious disruptions caused by the theft of cables or damage to public buildings this year, which costs local businesses and tax payers so much and even puts people’s lives at risk. There are still people attempting to remove high voltage cabling from electricity sub stations, which is extremely dangerous and likely to result in serious injury."

Anyone who has information about metal thefts is asked to call the police non-emergency number 101.