The UK energy price cap will rise by 13% from July after higher wholesale gas prices pushed up supplier costs.
Regulator Ofgem said the increase for the three months until September reflected volatility and higher wholesale prices in global gas markets stemming from the US and Israel's war on Iran.
The price cap, which applies to default tariffs, will increase annual bills for a typical household from £1,641 up to £1,663 under updated consumption assumptions.
Households on fixed tariffs, around 40% of customer accounts or roughly 22 million households, will not be affected by the increase.
It comes after the cap for the preceding April-June quarter had dropped 7% for the average dual-fuel household, primarily driven by government Autumn Budget decisions to remove specific policy costs from household bills.
Ofgem also pointed out prices remain well below the height of the energy crisis in 2022 when the government stepped in to cap bills at £2,500.
What's more, households are also now using around 7% less electricity and 17% less gas than at the last review of typical domestic consumption.
Gas prices are expected to rise faster than electricity prices, with electricity bills increasing by around 5%, while gas bills will rise by 24%, reflecting greater renewable generation and lower reliance on gas-fired power.
Tim Jarvis, Ofgem chief executive, said: “Today's price change reflects continued volatility in global energy markets. This means higher wholesale gas prices, driven by ongoing conflict in the Middle East, is impacting the price we pay for energy.”
He added: "We understand many will be concerned about rising prices. While energy use typically falls over the summer months, there are still practical steps households can take to manage costs, including exploring fixed tariffs or changing their payment method. Smart meter customers can also take advantage of half price or cheap electricity at the weekends."