German environmental activists are trying to stop a planned pipeline from Russia to Germany via the Baltic sea just days before the investment is scheduled to break ground, Polish Radio reported.

According to the Polish state broadcaster, German environmental protection organisation Naturschutzbund Deutschland appealed to a court in Greifswald, northeastern Germany, to stop, at least temporarily, the Nord Stream 2 pipeline from being built, Radio Poland reported.

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The organisation claims the pipeline will result in irreversible losses to the marine environment.

Earlier this year the organisation challenged a German-issued construction permit that would allow a Russian-German consortium to start building on May 15.

But a verdict is yet to be handed down.

If built, the Nord Stream 2 pipeline would supply around 55 billion cubic metres of natural gas a year from Russia to Germany under the Baltic Sea, circumventing Poland, the Baltic states and Ukraine.

Poland, the Baltic states and Ukraine all oppose the project.

The US State Department spokeswoman said earlier this year that the US government opposed Nord Stream 2 as the project would undermine Europe's energy security and stability.