Russian gas company Gazprom's offices in Germany were raided by EU competition regulators, people familiar with the matter said.
This comes as the EU watchdog ramps up its investigation into the company's gas supplies to Europe.
EU antitrust chief Margrethe Vestager in January asked gas companies including Gazprom about tight supplies after accusations the Russian giant was withholding extra production that could be released to lower rising prices.
Vestager was likely to intensify information gathering on Gazprom's European businesses, a person familiar with the regulator's thinking told Reuters last month.
The European Commission declined to comment. Gazprom Export said it had no comment.
Gazprom and the Kremlin have repeatedly denied withholding gas supplies, saying that all firm and long-term obligations have been met.
The EU competition watchdog raided the offices of Gazprom Germaniaa nd Wingas, one of the people said.
Bloomberg was the first to report the raids.
Companies found breaching EU antitrust rules face fines up to 10% of their global turnover.
Gazprom dodged a fine in 2018 after agreeing to reform its pricing arrangements and pave the way for rivals in eastern Europe following an investigation.