Moscow
"This string will be gradually filled to build the required inventory and pressure as a prerequisite for the later technical tests," Xinhua news agency quoted the Nord Stream 2 AG as saying in a statement on Monday.
The first string of the pipeline has undergone pre-commissioning activities to assure the pipeline integrity, while pre-commissioning steps for the second string are underway, it added.
Russia's gas industry giant Gazprom, which owns Nord Stream 2 AG, announced on September 10 the completion of construction of the flagship energy project, although the US has voiced opposition repeatedly.
The 1,230-km pipeline is expected to bring 55 billion cubic metres of natural gas annually from Russia to Germany via the Baltic Sea.
Gazprom intends to put it into operation before the end of the year.
The US has long claimed that the Nord Stream 2 is a geopolitical manoeuver by Moscow that will undermine Ukraine's role in transiting energy to Europe and increase European dependence on Russian gas.
But Germany and Russia have insisted that the project is purely commercial.
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