Russian energy giant Gazprom said Saturday it had asked German group Siemens to return a turbine it has repaired in Canada to ensure the Nord Stream pipeline delivering gas to Europe works.Gazprom started 10 days of maintenance on the Nord Stream 1 pipeline on Monday, with the European Union — particularly gas-reliant Germany — waiting nervously to see if the taps will be turned back on.Moscow had already wound down supplies by 60 percent in recent weeks, blaming the absence of the turbine.Despite Western sanctions on Russia over its military operation in Ukraine, Canada has agreed to grant what it has described as a time-limited and revocable permit for Siemens Canada to allow the machine's return.But Gazprom claims it has received no guarantees of it being sent back."On July 15, Gazprom submitted an official request to Siemens to obtain the documents [...] to allow the export of the gas turbine engine of the Portovaya station, a critical facility for the Nord Stream gas pipeline," it said in a statement."Gazprom is counting on the Siemens group to unconditionally fulfill its obligations relating to the repair and maintenance of gas turbine engines on which the reliability of Nord Stream gas pipeline operations and natural gas deliveries to European consumers rely."The annual work on the gas link was scheduled long in advance, but with relations between Russia and the West at an all-time low, some fear Gazprom might seize the opportunity to simply shut off the valves.