Nord Stream is a dual natural gas pipeline stretching from Russian ports in the Gulf of Finland to the coast of Germany. It will cover some 760 miles, passing through economic zones in Russia, Finland, Sweden, Denmark and Germany.
The project consortium, led by Russian gas monopoly Gazprom, said it completed more than 500 miles of the pipeline. Sections of it lie in the economic zones of all five participating countries, the project consortium announced Monday.
Gazprom seeks to diversify its European gas export options through Nord Stream. About 80 percent of all Russian gas bound for Europe heads through Ukraine's gas transit system but disputes between Moscow and Kiev exposed vulnerabilities in the current gas scheme.
Nord Stream will carry enough gas to supply more than 26 million European homes when both lines enter service in 2012.
Construction started in German waters in April.