The European Commission proposed Wednesday new rules to clamp down on illicit practices in wholesale energy trading, in a bid to make prices more transparent as it pushes for stronger competition in a market worth billion of euros.

The rules would prohibit use of insider information and outlaw manipulation on the electricity and natural gas markets where prices are pushed artificially high, the commission, the EU's executive body, said in a statement. Distributing false news or rumors that give misleading signals would also be banned.

The commission has been pushing for years to boost competition in the gas and electricity markets, both by proposing new legislation and by using its antitrust powers, in an effort to unite the 27 national markets and reduce prices for consumers.

"It is crucial to ensure EU level comprehensive rules which guarantee that citizens can be confident that prices are formed fairly and they can fully benefit from the internal energy market," EU Energy Commissioner Guenther Oettinger said.

Wholesale prices have a direct impact on how prices to final consumers such as households and businesses are determined, in spite of regulated tariffs in some countries.

With this proposal, the commission seeks to fill in a regulatory gap about energy trading, because other EU laws regulate only part of the natural gas and electricity derivative markets. Based on 2009 trading volumes, the electricity market's value--including spot and the more sizeable forward trading--is roughly estimated at EUR500 billion.

The new rules will ensure that, for example, an energy company won't be able to trade on the electricity market before disclosing that it will have to shut down a power plant, whose closing would have an impact on electricity prices.

The proposals must be backed by European governments and the European Parliament to become law, and the commission expects them to be operational in 2012.