Russian gas exporter Gazprom said on Saturday it expected Siemens to meet its obligations in full when servicing gas turbines needed for the reliable operation of the Nord Stream 1 gas pipeline and energy shipments to Europe.

Kremlin-controlled Gazprom has said it could not guarantee the safe operation of a critical part of the pipeline that runs under the Baltic sea to Germany because of doubts over the return of a turbine from Canada.

On Saturday, Gazprom said it had asked Siemens to show documentation that would allow the crucial turbine to be brought to a Nord Stream 1 compressor station.

"Gazprom is counting on the Siemens Group to unconditionally fulfil its obligations with regard to servicing gas turbine engines on which depend the reliable operation of the Nord Stream pipeline and natural gas supply to European consumers," it said.

A Siemens Energy spokesperson said this week the company's experts were "working intensively on all other formal approvals and logistics" after Canada said it was issuing a "time-limited and revocable permit" to exempt the return of the equipment from its Russian sanctions.

Physical gas flows through the Nord Stream 1 pipeline from Russia to Germany plunged on Monday as maintenance of the pipeline got underway until July 21. European governments, markets and companies are worried the shutdown might be extended due to what Russia calls a "special military operation" in Ukraine.

Gazprom's gas supplies to Europe through Ukraine remained stable at 41.6 million cubic metres on Saturday.