Centrica reinforced Ofgem boss Alistair Buchanan's recent warnings of a looming capacity squeeze following its financial results announcement on Wednesday.

The energy company is not expecting to have any new gas plant up and running for at least four years, which could mean “uncomfortably tight” capacity margins by 2017-2018, it said.

Group finance director Nick Luff said: “We have a couple of gas fired power stations that we are ready to start building when the timing is right.”

Investment won’t start until the government’s Energy Bill clears Parliament, which could be up to two years from now. That legislation will nail down a capacity mechanism to reward gas generators for having backup power available to balance intermittent renewables.

Gas plant take at least two years to build.