Russia's state-controlled natural gas monopoly Gazprom says that any expansion of Western sanctions imposed over Moscow's involvement in Ukraine could have serious consequences for Gazprom's business and share price.
The company also said in its financial report on April 29 that disagreements over gas prices with Kyiv could potentially disrupt its gas exports to Europe through pipelines that cross Ukraine.
Gazprom and its managers have not been included in U.S. or EU sanctions over Russia's actions in Ukraine.
Gazprom supplies 30 percent of Europe's gas demand.
Meanwhile, Japan said on April 29 it would deny visas to 23 Russian individuals as part of its sanctions against Moscow.
It did not identify those affected, but local media said Russian government officials were on the list.
The announcement came after Washington and the EU imposed fresh sanctions on Russia.
Based on reporting by Reuters, AFP, and ITAR-TASS