The European Union's executive body questioned Monday Russia's state-run energy giant Gazprom's (GAZP.RS) announcement last week that it had taken a final investment decision to build South Stream, a planned natural gas pipeline from Russia to Europe.

"It was never communicated to the (European) Commission that South Stream has a final route," said Marlene Holzner, spokeswoman for Energy Commissioner Guenther Oettinger. "We don't regard this as a final investment decision," she said.

The multi-billion euro pipeline would carry gas from
Russia to Europe , bypassing Ukraine , but its construction is still controversial, as the EU requires pipeline operators to offer part of the infrastructure's capacity to competitors, something that has created tensions with Gazprom, which owns many of the pipelines bringing gas to the EU. The region is heavily dependent on imports of Russian gas.

The 3,600-kilometer South Stream pipeline is expected to carry 63 billion cubic meters of gas to
Europe annually by 2015. Gazprom has said it will make supplies to Europe more reliable, but analysts have questioned whether it is needed.