By Laurence Norman 

BRUSSELS--The European Commission said Monday it had opened a probe into whether Luxembourg's tax treatment of French energy giant Engie SA breached European Union state-aid laws, the latest in a series of probes looking at past tax deals.

The commission, the EU's executive arm, said it had concerns that several tax rulings made in September 2008 by Luxembourg authorities may have given GDF Suez group, now called Engie, an unfair advantage over other companies.

In a press release, the commission said that several intra-group financial transactions appeared to allow the company to reduce their taxation on profits arising in Luxembourg.

As a result, the commission said, the company may have paid no tax on a "significant proportion of the profits" generated by the transactions.

"Therefore, we will look carefully at tax rulings issued by Luxembourg to GDF Suez," said European Union antitrust commissioner Margrethe Vestager. "They seem to contradict national taxation rules and allow GDF Suez to pay less tax than other companies."

The commission didn't say how much money might be at stake in the case.

In a statement following the announcement of the probe, Luxembourg's finance ministry said that the government "considers that no special tax treatment or selective advantage has been awarded to any Engie group company in Luxembourg."

The ministry said it would provide all the information the commission requests for the probe.

The Engie tax treatment probe comes after the commission in late August demanded that Ireland recoup roughly EUR13 billion ($14.5 billion) of unpaid taxes accumulated over more than a decade by Apple Inc., a move that intensified a feud between the EU and U.S. over the bloc's tax probes into American firms.

The commission is continuing to investigate Amazon.com Inc. and McDonald's Corp. over their tax arrangements in Luxembourg. Amazon has previously said it receives no special tax treatment from Luxembourg while McDonald's has said it "complies with all tax laws and rules in Europe."

Engie is one of several European firms that have also been targeted. Others include Fiat Chrysler Automobiles NV. However the car maker was only required to pay up to EUR30 million in taxes.

Write to Laurence Norman at laurence.norman@wsj.com

(END) Dow Jones Newswires

September 19, 2016 07:36 ET (11:36 GMT)