The EU's Gas Directive, which sets out similar regulations for all third country (i.e. non-EU) suppliers, was updated last year, Simson said.

"Perhaps we we are not just talking about Nord Stream, but all the other pipelines from wherever they originate," Simson told ERR's Epp Ehand.

"However, when these enter the EU zone they have to follow certain regulations. We are monitoring these in cooperation with the local agency – in this case the German Bundesnetzagentur," she added.

Simson said that in addition to being open to third country suppliers, the EU's gas network must have a clear tariff policy and be unbundled from the producer.

"It is not possible to start Nord Stream without complying with our rules," Simson said.

When asked whether this means the pipeline must be licensed before starting operations, and the pipeline owner and producer must be separated, Samson replied: "Absolutely. Every gas connection from a third country must comply with particular rules and this does not provide for any opportunity for Nord Stream to apply for an exemption."

Simson also said the EU has invested heavily in recent years to ensure that the union is not dependent on a single supplier, nor any one single route or transit corridor. 

"This has primarily been carried out by establishing gas connections between member states and also by investing in the liquified natural gas (LNG) network, since LNG is a form of gas that can arrive at EU member states from anywhere in the world," she added.

While Estonia does not have an LNG terminal at present, both Lithuania and Finland have, at Klaipeda and Tornio respectively.

"What's very important is that at the end of the year, we obtained a mediated negotiation between Ukraine and Russia and got a new five-year agreement for transit through Ukraine," she continued.

Since some of the companies constructing the pipeline are subject to U.S. sanctions, Simson was asked how the commission is dealing with this. She said that it was currently analyzing the impact on European businesses.

"It is true that the U.S. and the EU have issued sanctions for activities that do not comply with international law or do not comply with EU law. If the construction activity complies with the rules in force in the EU and the member states have authorized it, the sanctions require further analysis," she said.

Nord Stream 1 started its operations in 2011. Work on Nord Stream 2, running from Ust-Luga near St Petersburg, to Greifswald, close to Germany's Baltic coast, is scheduled for completion, at least according to Russian Federation President Vladimir Putin, late on this year or early next year. German chancellor Angela Merkel has expressed disagreement with the U.S. approach to sanctions.

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