The European Commission launched on Wednesday a controversial drive to prevent big EU members from negotiating their own direct energy deals, for Libyan oil or Russian gas for example.
"It is perfectly clear the success of any energy policy is dependent on a successful common external energy policy on behalf of the EU and its member states," Energy Commissioner Guenther Oettinger told a news conference.
The EU, home to half a billion consumers and about 20 million companies in 27 states, imports 80 per cent of its oil and 60 per cent of its gas requirements.
Launching a formal legislative proposal for European Commission vetting rights on hugely lucrative, and politically sensitive energy deals, Oettinger said he aimed to end "divine rule" on supply markets for the biggest external producers.
"If we speak with one voice, I think we have got a completely different weight," he argued, when it comes to negotiating.
It will "no longer be divine rule for successful third countries," insisted the German commissioner, who in the last year has fallen foul of the offshore oil and nuclear power industries with failed bids for a drilling moratorium and full-spectrum safety testing of atomic reactors.
The EU has in recent years faced a series of winter crises over gas supplies from Russia, amid rows over pricing or political in-fighting across the former Soviet bloc where transit pipelines through Ukraine, for instance, are critical to the supply.
"Individual, third country states aren't able to achieve as much," Oettinger said.
Diplomats have indicated deep unease among major EU political players and national consumer markets over what could be seen as a power grab.
Oettinger cited a centralised, European Commission-led negotiation with Azerbaijan, which he said has promised stable supplies at favourable rates for the long term.
"These are shared interests, that will contribute significantly to the security of supply for Europe's gas market," he insisted.
Oettinger argued also that the drive was motivated by a desire to guarantee common market rules are adhered to.