Energy regulator Ofgem has today announced plans to cap gas and electricity bills for up to four million UK households from April.

The cap follows an investigation into “competitive pricing” and is expected to save those on prepayment tariffs an estimated £80 a year on gas and electricity bills.

Ofgem said these are the most “vulnerable” customers, according to mirror.co.uk.

The fix, which will come into effect on 1 April, was one of the measures recommended by the Competition and Market Authority after its two-year investigation of the energy market.

It found that prepayment customers are being “denied the best deals”, when compared to those who pay by direct debit, cash or cheque and are therefore more likely to end up paying more for the same service.

The new fix is expected to stay until 2020 when the roll-out of smart meters is set to complete.