Pre-pay meters are making it more difficult for families to heat their homes according to research by Save the Children UK.
The report undertaken for the charity by YouGov discovered nearly one in five households with children have had to endure cold homes because they cannot afford the cost of energy.
The figures are even more severe amongst the least well-off with 44 per cent of families living on annual incomes of less than £15,000 reporting they had difficulty covering heating costs.
The charity says that one reason the UK's poorest families are hit hardest is because many rely on prepayment meters to heat their homes.
It calculates that on average the cost of paying for electricity and gas with a pre-payment meter is 26 per cent higher than paying via an online Direct Debit.
UK Poverty Spokesperson at Save the Children Phillipa Hunt said: 'We know that less well-off families are much more likely to use pre-pay meters, because it gives them the flexibility to plan a weekly budget.
“So by charging more for using pre-pay meters, energy companies are in fact penalising those families and children who are least able to pay.
”We want energy companies to bring their pre-pay charges in line with the cost of online Direct Debit.
”The government also needs to play its part. It should use the new Energy Bill to enforce minimum standards of social tariffs, so that people on low incomes are paying as little as possible for their energy.
”Fuel poverty is an outrage, particularly for children. It means that they are experiencing the effects of cold on a daily basis. Children find it more difficult to do their homework in a cold home, and are more likely to suffer ill health.”