The European Union launched a probe Thursday into iconic US fast food giant McDonald's tax deals with Luxembourg, widening an investigation into tax dodging by major multinationals.

The European Commission, the EU's competition regulator, "has opened a formal probe into Luxembourg's tax treatment of McDonald's," a statement said.

The case against one of the world's most iconic companies adds to a series of probes launched last year following the LuxLeaks affair, which revealed that top global companies had negotiated lower tax rates, in some cases as low as one percent, in secret pacts with Luxembourg.