A regular energy industry exercise aimed at preparing the UK for the possibility of a gas supply emergency has been scaled up despite the government downplaying the threat of shortages this winter.
The annual drill will see potential scenarios - including rationing electricity - wargamed over four days, rather than the usual two, as energy concerns grow.
Industry insiders linked the drill's extension to the seriousness of the energy challenges forecast this winter.
But the government says the exercise is a routine part of the energy industry calendar and insists there is no risk to gas supplies this winter.
The National Grid exercise, which will take place across four days in September and October, will involve government agencies, regulators, lobby groups and major energy firms.
Called Exercise Degree, it will simulate scenarios in which a loss of gas supply triggers an emergency situation for the UK's energy system.
