Households face a “dramatic and catastrophic winter”, a senior energy firm executive has warned ahead of the increase in the price cap on bills.

EDF managing director Philippe Commaret warned that half of UK households could be in fuel poverty in January as a result of rocketing energy prices.

His comments came as the National Grid prepared to hold an exercise to test the resilience of systems in the event of a gas supply emergency.

Consumers will find out on Friday how much the energy price cap will rise, with analysts expecting average annual bills to increase to more than £3,500.

Mr Commaret said EDF was launching a campaign to help customers cut bills with energy-saving measures but the scale of the problem meant further intervention from the UK Government was needed.

Regulator Ofgem will announce the new level of the price cap on Friday, with energy industry consultants Cornwall Insight warning that households will face an 80% rise in bills going into the winter period.

Energy prices are tipped to hit £3,554 from October, then rise to £4,650 from January.