The rules would explicitly forbid several forms of market abuse in power trading. They would also require those who trade gas and electricity to register with one of the European Union’s 27 member states and provide information about their transactions to authorities.

The volume of power traded in the EU nearly tripled between 2000 and 2009, thanks in part to a series of liberalisation packages that have sought to open up the continent’s gas and electricity networks to greater competition.

In addition to large energy companies, such as Germany’s RWE and France’s EDF, investment banks such as Morgan Stanley have also become active in the power markets.

Mr Oettinger and his staff became concerned that greater oversight was necessary because three-quarters of EU energy trading is conducted over the counter, as opposed to passing through exchanges, giving authorities little insight into the activity.

Their worries deepened after reviewing a high-profile scandal in the US involving the Amaranth Advisors hedge fund, which collapsed in 2006 after losing more than $5bn by betting on natural gas futures. The Federal Energy Regulatory Committee subsequently accused one of the firm’s traders of trying to manipulate NYMEX prices in order to benefit its swap positions on other exchanges.

Commission officials say they were not convinced that they would have been able to detect a similar case – or even if it would have been illegal in Europe. At present, many power and gas contracts are not covered by the EU’s existing legislation governing financial instruments, including the market abuse directive, and the markets in financial instruments directive, or MiFid.

The new rules are supposed to improve transparency by ensuring that national regulators receive transaction information – whether trades are conducted through exchanges or over the counter. Although the data will be handed to national regulators, European authorities will be able to access them in order to form a fuller picture of the continent’s trading.

Mr Oettinger called the rules “a huge step forward” that would improve market transparency. “It will build confidence in the market and will contribute to fair energy prices for consumers and businesses,” he said.