Energy Commissioner Andris Piebalgs told European lawmakers Nabucco was not endangered by Russian plans to expand its regional gas networks.
Russia aims to diversify its gas transit options in Europe through its Nord Stream and South Stream gas pipelines. Turkey is seen as a major host for Nabucco and South Stream, agreeing to host a leg of the Russian-backed gas pipeline following a recent visit to Ankara by Prime Minister Vladimir Putin.
"We have taken note (of the Russian-Turkish agreement), but we trust Turkey for Nabucco," said Piebalgs.
On Nord Stream, the commissioner said that project would contribute to energy diversity, refuting Lithuanian claims that the pipeline was not a priority, European news portal EurActiv reports.
"Nord Stream will strengthen our security of supply. It will not weaken it," Piebalgs said.
Russian energy giant Gazprom cut gas supplies to Kiev following a January row over gas contracts and debts. Around 80 percent of all Russian gas is funneled through Soviet-era pipelines in Ukraine.
Piebalgs sought to allay looming concerns about gas supplies as Europe braces for the winter heating season.
"Are supplies guaranteed for the winter? Yes, we will survive," said the commissioner.