Electricity from the first mini nuclear power stations in Britain would be likely to be more expensive than from large atomic plants such as Hinkley Point C, according to a government study.

Power from small modular reactors (SMRs) would cost nearly one-third more than conventional large ones in 2031, the report found, because of reduced economies of scale and the costs of deploying first-of-a-kind technology.

The analysis by the consultancy Atkins for the Department for Business, Energy and Industrial Strategy said there was “a great deal of uncertainty with regards to the economics” of the smaller reactors.