Russia's state-owned energy company and the world's largest exporter of natural gas, Gazprom, explained last week to its European customers that due to "force majeure" circumstances it will not be able to continue supplying gas through the Nordstream 1 pipeline.

The indication was reportedly sent to at least one major customer last week, on July 14, with the company predicting supply difficulties in Germany and surrounding countries due to extraordinary circumstances beyond its control, international media write.

The Nordstream 1 pipeline has been down since July 11, in a customary outage for a ten-day maintenance. However, following sanctions on Russia due to the military invasion of Ukraine, European Union countries fear that the equipment will not be reactivated on Thursday as planned.

Germany's largest Russian gas importer has disclosed that it has received a letter from Russia's Gazprom claiming "force majeure" as the reason for past and current shortfalls in gas deliveries, a claim that the German company has rejected.

The Russian gas giant cited alleged technical problems involving equipment that partner Siemens Energy sent to Canada for review and could not be returned due to sanctions imposed over Russia's invasion of Ukraine.

The operator of Nordstream 1 in Germany assured on Tuesday that the pipeline maintenance will be finished by July 21.