In its natural-gas contracts with European buyers, Russia's Gazprom has tried to invoke an "act of God" clause, arguing that it should not be blamed for recent or current drops in supplies.
The move raises questions about whether Russia is planning to permanently reduce or even halt flows of the vital fossil fuel to Europe in what could be a huge blow for the region's economy.
In a sign of Russia's pivot away from Europe and toward Asia, Gazprom's natural gas exports to China through the Power of Siberia line reached a record high.
According to the report, the letter was sent to customers on July 14. The declaration was retroactive to June 14.
Parties can be released from their obligations in contracts if there is force majeure.
According to Uniper, the Russian company claimed force majeure retroactively for past and current shortfalls in gas delivery.
A Uniper spokesman said that the force majeure claim has been rejected.
RWE said it had also received a force majeure letter. The company did not reply to the request.
Russia has cut its supplies of natural gas to Europe in the last few months due to the conflict in Ukraine. The export of a turbine from Canada has been delayed due to sanctions by Moscow.
Many analysts think that the supply reduction is politically motivated and that Russia has not made up the shortfall through other routes.
According to analysts, the move could be a sign that Russia is not going to restart natural gas exports through the Nord Stream 1 line. The European Union doesn't expect it to reopen after being closed for maintenance, according to the Wall Street Journal.
A record amount of fossil fuel was exported from Russia to China through the Power of Siberia line. The exports were carried out under a long term contract.
Since the beginning of the year, Russia's natural gas exports to China have increased. In a sign of the close economic and political ties between Russia and China, President Putin visited Beijing in February and struck new oil and gas deals.
China and India have increased their purchases of oil from Russia, with the Kremlin looking for new sources of revenue as Europe tries to cut back on its purchases.
The chief commodities strategist at Saxo Bank thinks that natural gas flows to Europe through the Nord Stream 1 will start up again.
The worst-case scenario of no gas has been supported by Russia's refusal to book additional capacity on other lines.
He said that the force majeure should not prevent a restart on Thursday at the 40% capacity level seen before maintenance began.
The political decision to squeeze the European economy even harder was the reason for anything less than that, according to Hansen.