Private apartments were also raided in Volkswagen's hometown of Wolfsburg and other cities, prosecutors told AFP, as police seek to secure documents and digital data that could point to those responsible for the deception of global proportions.
The raids came as Volkswagen's US chief prepared to face Congress, when he would tell a committee that he knew more than a year ago that the group's cars possibly breached pollution rules.
In testimony released ahead of his hearing before a congressional committee, Michael Horn offered a "sincere apology" over Volkswagen's use of a software designed to cheat pollution tests as he vowed full cooperation with the authorities to shed light on the scam.
The so-called defeat devices then turn off pollution controls when the vehicle is on the road, allowing it to spew out harmful levels of toxic gases.
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The shocking revelations have wiped more than 40 percent off Volkswagen's market capitalization, but the direct and indirect costs are still incalculable as the company risks fines in several countries and possible damages from customers' lawsuits.
In Germany, prosecutors from the state of Lower Saxony said raids were carried out to "secure documents and data carriers that, in view of possible offences, can provide information about the exact conduct of company employees and their identities in the manipulation of exhaust emissions of diesel vehicles".
Sites raided "include private apartments, and it is important to guarantee the privacy of these people", she said.
Volkswagen confirmed that it had "handed over" documents to prosecutors, adding that the company would provide the necessary support to the probe.