An absence of the equipment has been cited by Gazprom as the reason behind lower flows through the pipeline.

"Due to the sanctions imposed by Canada, it is currently impossible for Siemens Energy to deliver overhauled gas turbines to the customer," the company said.

"Against this background we have informed the Canadian and German government and are working on a viable solution."

(Reporting by Christoph Steitz; Editing by Jan Harvey)