Energy regulator Ofgem has warned the electricity network firms of UK by saying that they are putting the customers at an 'unacceptable' risk of power cuts in trying to maintain the country's ageing pylons and wires.

The energy regulator has raised this concern by sending a letter to the distribution network operators, which says that it will impose a penalty if distribution network operators fail improve their services, reported.

The network operators warned for failure of their services include Scottish Power, Scottish & Southern, Warren Buffett’s CE Electric and E.ON.

Ofgem threatened to impose fines to have a proportionate impact on shareholder returns.

The letter urges the network firms to be quicker in reporting any breaches of their engineering obligations during their work to keep the network in a good state.

The news agency quoted Ofgem distribution partner Rachel Fletcher as saying that the energy regulator wants to raise its concern that the approach that is being adopted by some distribution network operators to assess their compliance may be exposing customers to unacceptable levels of risk regarding security of supply.