The U.S. has threatened, but not levied sanctions on companies involved in building the Nord Stream 2 gas pipeline. Sanctions on the consumption of Russian gas have not been threatened.

"Sanctions against the use of Russian gas would be a violation of the sovereignty of Germany and Europe," Wolfgang Buechele said, adding that if it came to this he would hope to see a political reaction from Berlin

(Reporting by Thomas Escritt; Editing by Michelle Martin)