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MPs are calling for National Grid, the company that runs Britain’s electricity system, to be broken up in a radical move they say could transform the UK’s energy supply.

Members of the cross-party energy select committee have said they believe that National Grid, which is one of Britain’s 20 biggest companies with a market value of £36bn, faces too many conflicts of interest and should be split up.

Such a move could prove costly for shareholders. When Amber Rudd, the energy secretary, first proposed shaking up the way the company was run, its shares dipped noticeably, though they later recovered.

The company has three different parts to its business. It owns the wires and pylons that carry electricity around the country; it runs the system to make sure the lights stay on; and it owns assets such as interconnectors that bring power in from abroad.

The last of these functions has proved particularly profitable for the company in recent years as the UK has relied on electricity imports to keep the power running.

In May, it reported increased annual profits, partly on the back of £123m of operating profit from the interconnector with France, a 19 per cent increase on the previous year.

But critics say that the company should not own such a profitable asset while also running the system that procures the power from that asset. The company says it has put safeguards in place to keep the two functions separate.

Ministers are now consulting on how the company should be structured, with officials saying they have not ruled out splitting it up entirely.

Angus Brendan MacNeil, chairman of the committee, said: “National Grid’s technical expertise in operating the national energy system must be weighed against its potential conflicts of interest.”

His committee’s report goes further: “Unnecessary asset development, or giving interconnectors an unfair advantage over existing and emerging balancing tools, could dilute the impact of other efforts to develop low-carbon network infrastructure.”

National Grid said: “We take very seriously the need to provide confidence that any potential conflicts of interest are handled correctly and have a lot of experience operating in an environment where this is a key part of what we do.

“We are currently working with the government and with regulators to ensure we continue to manage potential conflicts as our role develops.”