According to Spiegel, Audi headquarters in Ingolstadt, Bavaria, were searched by police on Wednesday morning. A location in Neckarsulm was also searched by authorities. The company confirmed this to Spiegel.
Prosecutors in Munich have long been investigating whether the Volkswagen subsidiary Audi could also be held responsible for the so-called dieselgate scandal that erupted in 2015 as it emerged that 11 million cars worldwide had been equipped with software to deceived emissions tests.
More than two million Audis had the manipulation software, including more than half a million in Germany alone.
“I can confirm that the prosecutors in Ingolstadt and Neckarsulm are present,” an Audi spokesperson told Spiegel, declining to comment further, but adding that the company would “completely cooperate”.
A former head of diesel engine development, Ulrich Weiss, has accused Audi boss Rupert Stadler of knowing about the engine manipulation early on.
Volkswagen last Friday pleaded guilty to criminal charges against it in the US. It agreed to pay $4.3 billion in criminal and civil fines to settle charges.
Dieselgate took a toll on the parent company's reputation, and forced Volkswagen to set aside more than €22 billion for fines and compensation claims.