Independence could be a "bit of a nightmare" for the energy industry, with extra costs generated, according to the boss of the energy industry's trade body.

Former Treasury Minister Angela Knight has insisted that Great Britain's single market was important for the businesses and that regulatory policy needed to be the same if Scotland voted for independence.

"There needs to be a clarification on what happens to the subsidies for renewables as subsidies are socialised across the population," said the chief executive of Energy UK

"If you separate the country into two parts, then what are you going to do about the legal and regulatory issues and who licenses who and for what? Who licenses a generator in Scotland that supplies its electricity to England? It's a bit of a nightmare," she declared in an interview with the Huffington Post website

"If we end up with two regulators, two different sets of licence conditions and customer requirements, two wholesale markets and all that sort of thing, it is inevitably adding costs to the system," she warned.

A spokesman for the Department for Energy and Climate Change said: "Angela Knight raises important questions about the possible impacts of Scottish independence for the energy industry, our integrated single market and support for renewables in Scotland."

A Scottish Government spokesman said: "There are already examples across Europe of two or more independent countries coming together to participate in a single energy market and their co-operation on the licensing and regulation of the participants in those markets."