Construction of the Nord Stream Pipeline, which will link Russian natural gas reserves to Europe, has been officially launched.
The event was marked by the welding of two pipeline segments on the bed of the Baltic Sea, 30km off the Swedish island of Gotland.
The ceremony at Portovaya Bay was attended by Russian President Dmitry Medvedev, who said the pipeline would ensure stable Russian gas supplies to Europe.
Running from Vyborg in Russia to the German port of Greifswald, the 1,224km pipeline will be the longest sub-sea pipeline in the world when complete. It will transport up to 55bn cubic metres of gas a year from 2012.
A consortium of Gazprom, Winstershall, E.ON Ruhrgas, Gasuine and GDF Suez is investing €7.4bn ($10.1BN) in the project, which is expected to help Russia increase its share of EU gas markets from its current 25 per cent to about a third.