There were fresh fears yesterday about Britain's ability to keep the lights on this winter after it emerged that Norway has drawn up plans to ration electricity exports.
The Telegraph says the move has heightened worries about possible energy shortages in the UK and Europe later this year.
The Norwegian Government has just announced new rules limiting the sale of power to foreign countries as heatwaves threaten the country's hydro-electric power generation.
Experts said the restrictions threatened the UK's plan to draw power from Norway this winter via the North Sea Link - leaving electricity supplies more stretched and risking even higher bills for consumers.
The National Grid has already revealed that the UK is set to be more dependent than ever on the Continent for power, with interconnectors expected to provide up to 5.7 GW of electricity at peak times. About one quarter of that total is set to come from Norway.
Kathryn Porter, an energy consultant at Watt-Logic, told the Telegraph that the proposed restrictions put at risk the ability of Britain to import from Norway this winter.
"National Grid ESO needs to urgently update its winter outlook taking account of this threat to Britain's energy security," she added.
Rely less on imports
"Longer term, we need to develop more domestic generation and rely less on imports."
Consultants at Aurora Energy also warned that curbs on Norwegian power would push electricity prices higher because National Grid would be forced to call on coal-fired plants as backup.
Asked about the Norwegian plans, a National Grid spokesman said the company would update its winter forecasts to ensure they are "as robust as possible" in the autumn.
Norway generates almost all of its electricity from hydro-electric power stations and has been called the "battery of Europe".
Its hydro-electric plants usually provide an abundant source of cheap power, but water levels in the reservoirs are currently a third below what is typical for this time of year and take months to be replenished by rain and melting snow.
Terje Aasland, the country's energy minister, said Norway's centre-left government would respond with new regulations that would force power companies to limit electricity exports when the levels dip too low and instead prioritise refilling reservoirs to protect energy security.
He said the changes were necessary after dry spells in the spring and summer left water levels at historic lows.
Tough winter
Europe is bracing for a tough winter, with Russia choking off supplies of gas to the Continent and France's nuclear power stations laid low by technical issues.
Paris on Monday extended a temporary waiver to environmental rules for nuclear plants to help keep reactors running as resources are stretched thin.
State-owned nuclear power giant EDF will be allowed to discharge hot water from five plants into rivers, even if the temperatures breach rules usually in place to protect waterways.