A major fire has forced the shutdown of one of Britain’s most important power cables importing electricity from France as the UK faces a supply crunch and record high market prices.

National Grid was forced to evacuate staff from the site of the IFA high-voltage power cable, which brings electricity from France to a converter station in Kent, where 12 fire engines attended the blaze in the early hours of Wednesday morning.

The fire has halted electricity imports via the 2,000 megawatt power cable until March next year and could not have come at a worse time for the UK’s squeezed markets, according to experts. The UK faces record energy prices after a global gas market surge raised the cost of running gas power plants, which has been compounded by a string of power plant outages and low wind speeds.

The all-time energy price highs are expected to send bills soaring for the next year and cause a string of small energy companies to go bust. It has already forced some steelmakers to shut their factories during hours of peak electricity demand.

The market price at one of the UK’s main electricity auctions cleared at a record price of GBP2,500 per megawatt-hour for the hours of peak demand on Wednesday, compared with a typical baseload price of about GBP40/MWh throughout 2019 and 2020.

Phil Hewitt, a director of the market consultancy EnAppSys, said the fire was “a major event” because it could lead to an extended outage at the IFA cable.

“It puts the GB market in a risky position for the winter and especially if we suffer from periods of low wind and cold temperatures,” he added.

The electricity system operator, which is owned by National Grid, said there would be enough electricity to meet the UK’s peak demand on Wednesday evening. However, market experts fear the latest blow to the UK’s power system could cause prices to rise further and will increase the UK’s reliance on running its last remaining coal plants.

Gareth Stace, the director general of trade group UK Steel, said the “extortionate prices” were forcing some steelmakers to suspend work during periods when electricity prices were at their highest. He called on the government and the industry regulator to “take action as this situation continues”.

“Last year, prices were roughly GBP50 per megawatt hour. Even with the global steel market as buoyant as it is, these eye-watering prices are making it impossible to profitably make steel at certain times of the day and night,” he said.

“Electricity prices increase in the winter months, therefore the situation gets more urgent each and every day,” Stace added.

National Grid confirmed that the West Burton coal plant in Nottinghamshire and a coal unit at the Drax site in North Yorkshire were warming up in anticipation of generating electricity on Wednesday evening in exchange for eye-wateringly high payments.

Last week the electricity system operator paid about GBP4,000/MWh to power plants that could generate electricity at short notice, and a total of more than GBP86m to keep the lights on. The Ratcliffe-on-Soar coal plant near Nottingham is also in line to benefit from record power prices this week.

Kent fire and rescue service said on Wednesday afternoon that four fire engines, two height vehicles and its technical rescue unit remained in attendance at the IFA site. National Grid said it would provide an update on the incident in due course.