The European Commission, which is due to rule on Russia’s plans to pump more gas to Germany via a land link from its Nord Stream pipeline, says it needs more details from German regulators before making a decision.

The EU’s energy chief told Reuters on Wednesday that it had asked Germany’s energy regulator, Bundesnetzagentur, to provide the information and expected to receive it in September.

Germany struck a deal in May to let Russian state energy producer Gazprom pump more gas through the Opal link, but the plan needs the Commission’s approval as it bypasses EU anti-monopoly rules that cap Gazprom’s use at half of Opal’s capacity.

Russian pipeline plans have become increasingly politicized due to Russia’s conflict with Ukraine. The EU executive has already delayed making a decision on the Opal link.

Full access to Opal, which provides a land link between Russia’s Nord Stream pipeline to Germany and the Czech Republic, is crucial to Gazprom’s plan to double capacity of the undersea pipeline in a project known as Nord Stream 2.

The expansion of Nord Stream would see more Russian gas bypass Ukraine – a move seen depriving Kiev of transit fees as the route for more than half of Russian gas supplies to Europe.

European Commission Vice-President Maros Sefcovic, the EU’s energy chief, said the EU executive will not be ready to rule on whether to approve the German deal with Gazprom until it is in possession of all the details.

“The Opal dossier is being currently examined and there were some additional questions raised by the Commission,” Sefcovic said. “Whether we are ready to take a decision or not depends on the completeness of the answers.”

Because Gazprom is also part-owner of the Opal pipeline, it is regulated by a 2009 EU law, known as the Third Energy Package, that seeks to prevent energy suppliers from dominating infrastructure.

Gazprom has long fought an EU decision limiting its access to the pipeline, but talks on reaching a settlement collapsed in 2014 after Russia’s annexation of Ukraine’s Crimea region.

Gazprom and its European partners, which include E.ON, Wintershall, Shell, OMV and Engie, agreed the Nord Stream 2 project last year.

A positive ruling on Opal would help smooth the way for Gazprom to build Nord Stream 2, which has not received EU regulatory approval. Sefcovic has cast doubt on the need for expanding Nord Stream.

“If the commercial decision is taken that they still want to go ahead, then it should be done within the legal framework of the EU,” Sefcovic said. “We are looking at how the EU law can be respected in all its aspects.”