The European Commission took on Russia and dominant European power giants in a new move to open gas and electricity markets to more competition while limiting foreign ownership of EU assets.
The European Union executive adopted hard-fought energy proposals aimed at forcing big utilities such as Germany's E.ON and Electricite de France to separate power generation from their distribution networks.
Under the plan, generators will be forced to sell their transmission networks or hand over control to an independent operator, which the Commission argues will boost investment in infrastructure and allow new entrants into the sector.
But Russian gas monopoly Gazprom, which supplies about a quarter of the 27-nation bloc's gas, and Algeria's state-owned Sonatrach will not have free rein to buy pipelines and power grids.
The new rules will bar foreign firms from controlling European energy networks unless they play by EU rules and their home country reaches an agreement with Brussels, Commission President Jose Manuel Barroso said.
"In practice, third-country individuals and companies should not be able to acquire control over Community transmission networks unless there is agreement between the Community and their country of origin," he told a news conference.
A Commission statement said Brussels could intervene when a potential purchaser "cannot demonstrate both its direct and indirect independence from supply and generation activities".
In a statement issued before the proposals were published, Gazprom stressed it was a reliable gas supplier to the European Union and wanted a say in future regulation.
"Gazprom has an important contribution to make to the debate about regulation of the energy sector in Europe and feels certain that its voice will be heard," company spokesman Sergei Kupriyanov said.
The Commission argued over details of the package up to the last minute in a sign of their political sensitivity.
Transport Commissioner Jacques Barrot of France wanted utility groups to have more say over transmission networks even if they were run by an independent operator, EU sources said. Energy Commissioner Andris Piebalgs and Barroso reject that view.
The Commission has long favoured full "ownership unbundling", which would force companies to sell their pipelines and grids.
But several EU states, including France and Germany, oppose it, so the Commission offered an alternative of an independent system operator (ISO) to run distribution networks. Each member state would be free to choose between the two options.
Piebalgs insisted the Commission had not watered down its proposal on the independent operator.
Barroso said he was confident a clear majority of member governments would support the energy package, but said: "Of course now discussion starts on the concrete proposals and let's be honest: it will be a tough, long, difficult negotiation."
A senior German official was quoted on Wednesday as saying Brussels' proposals to break up big utility companies were almost tantamount to expropriation.
"The plans go too far," Joachim Wuermeling, secretary of state in the Economy Ministry, told Financial Times Deutschland. "The proposals come very close to a de facto divestiture."
Other elements of the new rules include strengthening the role of national electricity and gas market regulators and the formation of an Agency for the Cooperation of Energy Regulators. Legal issues surrounding the creation of the agency were also still being debated, the sources said.