Russia has imposed sanctions against units of Gazprom Germania and dozens of other companies based in countries that have imposed sanctions on Russia in response to its invasion of Ukraine.
Under the sanctions, the 31 companies listed on May 11 by the Russian government are banned from conducting transactions and entering Russian ports.
But it notably includes local subsidiaries of Gazprom, which supplies more than a third of European gas.
The list also includes EuRoPol GAZ SA, the owner of the Polish part of the Yamal-Europe gas pipeline through which much of the Gazprom gas supply to Europe flows. Other EU firms as well as U.S. and Singaporean energy companies are also named.
German regulators took control of operations at Gazprom Germania after Gazprom abandoned it last month without explanation.
The German Economy Ministry is examining the announcement, a spokesperson for the ministry said. The ministry said the supply of gas is constantly being checked and currently is guaranteed.
"The German government and Federal Network Agency, as trustees of Gazprom Germania, are already in the process of taking the necessary precautions and preparing for various scenarios," the spokesperson said in a statement.
Gazprom Germania's operations span supplies to wholesalers and retailers, storage, and pipeline transmission. Its operations include Germany's biggest gas storage facility at Rehden in Lower Saxony.
Under a decree issued by President Vladimir Putin on May 3 no Russian entity is allowed to make deals with the entities under sanctions or fulfil its obligations under existing deals.
The decree explicitly forbids the export of products and raw materials to people and entities on the sanctions list.
Putin framed the decree as a response to sanctions imposed by the United States and its allies.
Putin repeatedly warned that Moscow would respond in kind, though until last week the Kremlin's toughest economic response had been to cut off gas supplies to Poland and Bulgaria and demand European customers pay for gas in rubles.