The European stance on the planned South Stream gas pipeline from Russia is unclear but the project is progressing, a Russian presidential aide said Wednesday.

The European Commission is working to fill its 28 seats with new members, something that happens every five years. Yuri Ushakov, an aide to Russian President Vladimir Putin, said some potential host countries were idled by the European movements.

"It has been made clear to Serbia that it will find it next to impossible to implement this project without a go-ahead from Brussels, although [Serbia] is more than ready," he told journalists.

Serbian Foreign Minister Ivica Dacic said from Moscow last week preparatory work for the project was proceeding as planned, but "all other matters" related to the pipeline need to be settled by Russia and Brussels.

Ushakov said that, with new members coming to the European Commission, pipeline planners are "still to learn about Brussels'" stance on the project.

Members of the European Parliament in September passed a resolution calling on "EU countries to cancel planned energy sector agreements with Russia, including the South Stream gas pipeline."

South Stream is touted by Russia as a way to add diversity to a gas transit network dependent on trilateral ties between Brussels, Kiev and Moscow.

Most of the Russian gas for Europe runs through Ukrainian pipelines and conflict there makes that conventional route risky.