LONDON — Britain’s energy regulator is planning to authorize urgent investment to increase gas pipeline imports from continental Europe this winter, amid fears over the country’s ability to supply all customers in an emergency scenario. 

The plans, outlined in a document published Thursday morning, have been published a day after Energy Secretary Miatta Fahnbulleh approved a controversial North Sea gas project, Jackdaw.  

Government documents show that gas security considerations were given “substantial weight” in her decision. 

In a consultation paper, Ofgem said that, without intervention, Britain would have a “negative supply margin” this winter, in the event of a one in 20-year cold day — a day so cold Britain would only be expected to have one every 20 years — coinciding with the loss of key gas infrastructure. 

This unlikely scenario is a key standard followed by Britain’s energy authorities to assess its resilience in maintaining gas supply — also called the “N-1 gas security” standard. 

A shortfall in gas supply would be a national emergency, potentially requiring power plants or factories to shut down, or in extreme cases homes being disconnected from the gas network.  

Britain has never experienced a “network supply emergency,” but diminishing domestic supply and the threat of Russian sabotage of key undersea gas pipelines has raised fears over the country’s energy security. 

Last year the energy system operator, NESO, said long-term declines in domestic North Sea gas supply and global competition for LNG imports could mean the N-1 gas security standard is breached in winter 2030/31. 

However, there are now fears of a crunch point as soon as this winter, after the Belgian operator of the undersea gas pipeline Interconnector said it would cut planned export capacity to the U.K. because of soaring maintenance and operating costs. EU countries are also facing concerns over gas supply this winter. 

Ofgem, the regulator, said it is now planning to amend gas system operator National Gas’s regulatory licence, allowing them to cover the costs of maintaining imports from Belgium at current capacity, in agreement with Interconnector Ltd, majority-owned by Belgian firm Fluxys. 

“Without intervention, Great Britain could potentially face a negative supply margin in winter 2026/27 involving extremely high gas demand on a 1-in-20 cold weather day and the loss of the single largest element of GB gas infrastructure,” Ofgem said. “The position could become more constrained in future winters without intervention. While these are low-probability stress scenarios, their potential consequences are significant.” 

Costs will be recouped through customers’ energy bills. Ofgem said costs of £147 million could be passed on to bills, adding an estimated £1.19 to every domestic energy bill per year over a five-year period.  

Interconnector Ltd said it would restore British import capacity to 27.8GW this winter, an additional 11.3GW of capacity above the previously announced level. 

National Gas welcomed the plans but insisted that the warning over gas security “should not be interpreted as an indication that gas shortages are expected.” 

The Conservatives’ Shadow Energy Secretary Andew Bowie called the situation “utterly outrageous.” 

Britain is “going cap in hand to Europe and paying vast sums to import foreign gas,” he said, criticizing the Labour government for what he characterized as a failure to fully exploit domestic gas supplies. 

“Britain has one of the most secure and resilient energy systems in the world– and gas interconnectors form part of our diverse energy mix,” Energy Minister Michael Shanks said in a statement. 

“We are working with industry to build a gas system fit for the future, ensuring value for money for consumers while giving investors’ confidence to back Britain’s energy sector.”