Russian state-controlled gas giant Gazprom has announced its suspension from September 10 of purchases of natural gas from "independent" Russian suppliers.
Gazprom's information agency said the decision affects only the parent company and not any of Gazprom's subsidiaries.
Gazprom said the suspension was necessary due to a "significant reduction" in gas consumption.
The Russian company gave no indication how long the suspension would last.
Some of the independent suppliers affected by the announcement are Novotek, LUKoil, and Sibneftegaz.
The European Commission announced a formal investigation
in early September into Gazprom's dominant position in Central and Eastern Europe's gas markets -- including the company's practices in Bulgaria, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, and Slovakia. Other countries could be included later.
Russian President Vladimir Putin lashed out at the EU
over the Gazprom dispute, saying the bloc's move was "unconstructive" and suggesting Brussels was motivated by a desire to get Russia to "subsidize" the economies at issue.
Speaking on the sidelines of the annual summit of Pacific rim nations, Putin said the EU's action was prompted by the "difficult economic situation in the eurozone."
Based on reporting by "Vedomosti" and Interfax