Audi CEO Rupert Stadler. File photo: Michael Sohn / AP

Munich, Germany - The head of Volkswagen's luxury arm Audi has been arrested, the most senior company official so far to be taken into custody over the German carmaker's emissions test cheating scandal. Munich prosecutors said Rupert Stadler was being detained due to fears he might hinder an ongoing investigation into the scandal, plunging Volkswagen into a leadership crisis.

News of the arrest comew as VW's new group CEO Herbert Diess is trying to introduce a new leadership structure, which includes Stadler, and speed up the group's shift towards electric vehicles in the wake of its emissions scandal.

"As part of an investigation into diesel affairs and Audi engines, this office executed an arrest warrant against Professor Rupert Stadler on 18 June 2018," the Munich prosecutor's office said. A judge had ordered that Stadler be remanded in custody, it said, to prevent him from obstructing or hindering the diesel investigation.

ALSO READ: Volkswagen to pay 1 billion euro #Dieselgate fine

Audi and VW confirmed the arrest and reiterated there was still a presumption of innocence for Stadler. Stadler himself was not immediately available for comment. A spokesman for Porsche SE, the company that controls VW and Audi, said Stadler's arrest would be discussed at a supervisory board meeting on Monday.

VW admitted in September 2015 to using illegal software to cheat US emissions tests on diesel engines, sparking the biggest crisis in the company's history and leading to a regulatory crackdown across the auto industry. The United States filed criminal charges against former VW CEO Martin Winterkorn in May, but he is unlikely to face US authorities because Germany does not extradite its nationals to countries outside the European Union.

The Munich prosecutors said Stadler's arrest, at his home in Ingolstadt in the early hours of Monday, was not made at the behest of US authorities.