"We don't expect the first natural gas to arrive till 2012," said Andreas Hieckmann, the project chief at the Gazprom Germania company.

His comment clashed with a printed news release from Nord Stream, a consortium with Russian, German and Dutch involvement, which stated that 2011 was the target for the first flow.

He was speaking in Waren, north of Berlin, where Gazprom is studying the suitability of a bed of deep rock to store the gas in after it lands.

Nord Stream said it aimed to complete a multinational environmental review of the undersea route by the end of this year.

Unfair advantage?

Sweden has echoed environmentalists who fear the seabed trench for the pipes may kill sea life and stir up toxic material. Poland has led strategic criticism, saying Russia may gain a massive advantage by piping the gas outside the borders of intermediate nations.

Hieckmann said he expected delays because dumped wartime ammunition would have to be recovered from the Baltic seabed before the pipeline is laid and because of the "political friction" in the permissions process.

"Even if the regulatory procedures go according to plan, it will be a complex construction job," he said.

When complete, the line will transport 27.5 billion cubic meters (971 million cubic feet) of gas annually to western Europe. After landing on the German coast, the line will split, with one, codenamed NEL, bound west, and the other, the OPAL, bound south.