Speaking at the annual conference organised by the Ljubljana-based European Agency for Cooperation of Energy Regulators (ACER), Oettinger said that EU members must seek solutions for the implementation of the common energy policy.

The commissioner said that energy policy was still overly dictated by national interests, although he assessed that members more or less understood that a common market will benefit everyone.

"When markets integrate, we gain in efficiency, in economies of scale and in security of supply," he said.

Oettinger highlighted that the EU's various internal markets for goods have been functioning for decades, delivering advantages to both producers and consumers.

Moreover, he assessed that ACER was playing a key role in building an internal market. "It is an essential European partner in the development of network codes that harmonise how networks are integrated in the EU."

Oettinger's message was echoed by ACER director Alberto Pototschnig, who told the opening of the conference that while the EU had made great strides towards establishing an internal energy market, the task was far from finished.

Pototschnig stressed that merely setting down rules was not enough. It must be ensured that these rules are also implemented, he said, adding that consumers will otherwise not be satisfied.

The director said ACER's second annual conference was dedicated to debating what needs to be done to ensure that internal markets for natural gas and electricity are up and running by the target year of 2014.

The conference was also addressed by Slovenian Infrastructure and Spatial Planning Minister Samo Omrzel, who said that, in spite of delays in implementing the EU's third energy package, Slovenia was committed to an open market and allowing consumers to decide on their suppliers.

Omerzel also stressed that high quality infrastructure must be a priority of a common European energy market.

As part of the event, Omerzel and Oettinger held a meeting which focused on the development of the South Stream gas pipeline project, of which Slovenia is a part. The talks discussed the conformity of the project with rules from the EU's third energy package from 2009.

The rules dictate that distribution and sale must be separated from the operation of infrastructure, but Russian energy giant Gazprom, which is developing South Stream with European partners, opposes this given that it is both a seller and operator of energy infrastructure.

Asked whether the European Commission was willing to grant an exemption for South Stream, Oettinger said it was too early to say as it lacked official information on the project. "We don't even have an official request for an exemption," he said.

ACER's one-day conference ran under the title "Energy Markets: 2014 and Beyond" and saw strong participation from energy industry associations representing both producers and consumers as well as regulators and decision-makers.

Launching in March 2011, ACER an independent European institution which fosters cooperation among European energy regulators. It ensures that market integration and harmonisation of regulatory frameworks are done in respect of the EU's energy policy objectives.