Great Britain is expected to pay some of the highest energy costs in Europe this winter as its reliance on imports to ensure a steady supply is forecast to deepen.

Energy system operators have said the country will have enough gas and electricity to meet demand over the coldest months – in part because of paying higher market prices than neighbouring markets to secure imports.

The official winter energy forecasts were published days after Europe’s gas market benchmark climbed to its highest level since December 2022 when Russia’s full-scale invasion of Ukraine sent prices rocketing.

National Gas, which runs Great Britain’s gas networks, set out its forecasts after striking an 11th-hour deal with the owner of a major Belgian pipeline to keep gas flowing into the country this winter by reversing a planned capacity cut.

The energy regulator, Ofgem, approved the deal – which will add around 10p a month to the average gas bill.…