BERLIN (AP) — German Chancellor Angela Merkel has called Volkswagen's emissions-rigging scandal a "far-reaching event" and demanded the world's largest automaker quickly investigate it.

Merkel told German public radio Deutschlandfunk on Sunday she hopes "that VW quickly establishes the needed transparency and clear things up."

The extent of the fallout from the scandal, which erupted Sept. 18 when the U.S. Environmental Protection Agency said VW had cheated on tests of its diesel cars, remains unclear as do the costs to Volkswagen. Longtime CEO Martin Winterkorn quit last month, but said he was aware of no wrongdoing on his part.

Volkswagen AG has admitted using a piece of engine software to cheat on diesel car emissions tests. The company says that up to 11 million vehicles worldwide were fitted with the engine in question.