Britain's energy regulator has announced a price cap that could save more than 4m households around £80 per year.
Ofgem's temporary cap on prepayment meters is one of the results of the Competition and Markets Authority (CMA)'s two-year investigation of the energy market.
The levels of the cap vary for electricity and gas, by meter type and region, but Ofgem estimates many prepayment customers will see reductions in their gas bill of around 10 to 15 per cent from April, or around £80 a year based on a typical household's consumption.
The CMA found competition among prepayment meter suppliers is less developed than for those who pay by direct debit, cash or cheque, meaning customers have fewer tariffs available to them, and the tariffs they do have are generally more expensive.
Dermot Nolan, chief executive of Ofgem, said: "This temporary cap will protect these households as we work to deliver a more competitive, fairer and smarter market for all consumers.”
The cap will expire at the end of 2020 when the roll out of smart meters is set to be completed, which will help prepayment meter customers in particular access better deals.
Last month it was revealed the cheapest energy deal on the market rose £100, or 14 per cent, in just six months, while the big six energy suppliers have hiked their cheapest deals by an average of £135, or 16 per cent, since September.
Business and energy secretary Greg Clark called the price cap a "step in the right direction".
"It builds on our work to make sure the energy market works for everyone – not just those who switch suppliers – and follows action taken in December to increase transparency so people can see when they’re paying too much for their energy," he added.