Energy company Central Networks is appealing to anyone who has information about the thefts to contact the police.

The firm is offering a reward of �1,000 for information leading to the conviction of copper thieves.

Central Networks spokesman Alan Raymant said there had been nine major incidents in just two months.

This is a national problem... that we're taking very seriously Central Networks spokesman Alan Raymant

"These reckless criminals are smashing their way into our substations and breaking into our vital equipment with little regard for their own lives, for our engineers or for the huge inconvenience they're causing our customers.

"This is a national problem and, with over 97,000 substations across central England, it's a problem that we're taking very seriously.

He called on the public to become "our eyes and ears" by providing information about who is committing these crimes.

Mr Raymant said a charred hacksaw was found at one site in Northamptonshire and police managed to catch thieves in Clowne, Derbyshire, who were trying to steal copper from a substation.

In another incident on 21 August, a young man was trapped after breaking into a substation in Melton Mowbray. More than 3,300 customers were without power for 15 minutes while he was removed by emergency services.