Brussels will tomorrow accuse Russia’s energy giant Gazprom of illegal abuse of its dominant position in Europe’s gas market, unleashing antitrust charges that threaten to inflame already difficult relations with Moscow.

Just a week after confronting Google over its market power, Margrethe Vestager, the EU competition chief, is pressing forward with a longstanding Gazprom case all but frozen by the Ukraine crisis, according to two people familiar with the situation.

The decision to send a formal statement of objections is a gamble for the European Commission. It has always insisted it was treating Gazprom as it would any other company operating in Europe, despite the geopolitical implications such a case could have. Russia sees the probe as a political weapon.