The parliament's petitions committee also criticized the way in which the pipeline was planned by Germany and Russia without EU involvement, saying that this had damaged the scheme's credibility and political support.

And it called for the EU to create a high-level post in the office of the bloc's foreign affairs chief to oversee such projects in the future, in an implicit challenge to the EU's stance that energy projects should be weighed on their technical merits alone.

The Nord Stream project was launched by Germany and Russia in late 2005 and is aimed at bringing Russian gas to the German market under the Baltic Sea, thus bypassing transit states such as Ukraine.

But it quickly ran into opposition from new EU members such as Poland, who complained that they had not been consulted and warned that the pipeline could disturb some of the 80,000 tons of chemical weapons dumped in the Baltic after World War II.

Tuesday's motion, which followed petitions from Polish and Lithuanian environmental groups, called on the EU to use "every means at its disposal" to block the project if independent studies prove there is a risk of environmental disaster in the Baltic.

The report also demanded that Nord Stream's backers -- Gazprom and German firms EON Ruhrgas and BASF/Wintershall -- study the feasibility of running the pipeline overland before they take the undersea route.

EU aiming to prevent Gazprom influence over markets

And it called on the European Commission to stop Gazprom "assuming a dominant role on the EU gas markets without guaranteeing reciprocal rights for EU companies to enter the Russian energy market."

Nord Stream was quick to respond to the vote, saying that the text approved by the committee was "misleading" and prejudiced.

"The pipeline has been planned with a profound awareness of the environmental issues and conditions of the Baltic Sea," the company said in a statement.

The motion, approved by 26 MEPs with three votes against, is now set to face a vote in parliament in July. However, even if the motion is approved there, its importance will remain largely symbolic, as the parliament has no authority to approve or ban such projects.