By Hui Min Neo and Paul Handley
German police have swooped on Volkswagen's headquarters, carrying away files and hard disks in their investigation into a massive pollution cheating scandal engulfing the auto giant.
Private apartments were also raided on Thursday in Volkswagen's hometown of Wolfsburg and other cities, prosecutors told AFP, as police sought 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 faced a grilling before Congress, where he told a committee that he knew more than a year ago that the group's cars possibly breached pollution rules.
But Michael Horn said he did not know until "a couple (of) days" before September 3 that "defeat devices" had been installed deliberately in the vehicles to help them cheat pollution tests.
The German auto giant sank into the deepest crisis of its history after revealing that it equipped 11 million of its diesel vehicles worldwide with software that switches the engine to a low-emissions mode during tests.
The defeat devices then turn off pollution controls when the vehicle is on the road, allowing it to spew out harmful levels of toxic gases.
The shocking revelations have wiped more than 40 per cent off Volkswagen's market capitalisation, but the direct and indirect costs are still incalculable as the company risks fines in several countries and possible damages from customers' lawsuits.
Horn told the congressional committee that although he found out that the emissions of VW diesel cars did not meet US regulations in early 2014, "I was not then told nor did I have any reason to suspect or to believe that our vehicles included such a device."
"At that point of time, I had no understanding what a defeat device was. And I had no indication whatsoever that a defeat device could have been in our cars."
Admitting that the company had "broken the trust of our customers, dealerships, and employees, as well as the public and regulators", Horn apologised, saying: "We at Volkswagen take full responsibility for our actions and we are working with all relevant authorities in a cooperative way."
Underlining the uphill task to winning back confidence, Congressman Peter Welch said: "VW is the Lance Armstrong of the auto industry" - a reference to the US cyclist who had to be stripped of seven consecutive Tour de France titles after he was caught doping.
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".
Volkswagen confirmed that it had handed over documents to prosecutors, adding that the company would provide the necessary support to the probe.
A spokesman said it was "also in the interest of Volkswagen" for there to be "a prompt and thorough explanation" of the scandal.