Several of the UK's major energy suppliers are to seek backdated bills as a result of updates applied to their prepayment meters, reports the Daily Mail.
Many token-fed prepayment meters have not been recalibrated by energy suppliers to reflect price rises over recent months and so when they are replaced and updated many homeowners will receive a bill to cover the unpaid costs.
Prepayment meters are already controversial as they often command a price premium, despite more often than not being used by low-income households.
Ed Miliband, the energy minister, told the Mail: "I would urge all companies to ensure that some of the poorest people in society are not landed with back-payment demands they can't meet."
Mr Miliband added that he was "disappointed" that some of the UK's energy suppliers would be allowing their customers to fall into long-term debt.
Customers who are unhappy can choose to switch energy supplier in a bid to access cheap energy rates, although lower tariffs have recently been introduced in response to a fall in wholesale costs.
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