Belgian authorities have launched an investigation into energy giant GDF Suez on suspicion of tax evasion that may have involved price increases for consumers, local media reported on Saturday.

The energy giant is believed to have overcharged its Belgian subsidiary Electrabel by at least 500 million euros (685 million dollars) in 2012, local newspaper L’Echo reported citing a confidential report by the Belgian energy regulator CREG.

As a result, Electrabel’s customers are estimated to have overpaid by 255 euros on average over the course of the year.

The Belgian government, meanwhile, is said to have lost out on almost 170 million euros in tax revenues it would otherwise have collected from the company, according to L’Echo.

“The only one to benefit from this set-up is the GDF Suez shareholder,” the newspaper quoted the CREG report as saying.

GDF Suez on Saturday rejected the allegations contained in newspaper reports, the Belga news agency reported. The company had “no knowledge” of a tax investigation, but said it would cooperate if there was one under way.

Representatives of Electrabel also claimed not be aware of the investigation.

GDF Suez, which operates in more than 30 countries, reported revenues of 97 billion euros for 2012. In Europe, it is active in key markets such as Britain, Germany and Spain.

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