BERLIN (Reuters) -- German prosecutors raided Volkswagen's headquarters and other offices as part of their investigation into the carmaker's rigging of diesel emissions tests.
Prosecutors from Brunswick, close to the German company's home town of Wolfsburg, said they were targeting documents and data storage devices that might help with their inquiries.
The raid was carried out on Thursday by three prosecutors and about 50 police officers, who searched Volkswagen office buildings and private residences in Wolfsburg, a spokeswoman for the prosecutor’s office told Automotive News Europe.
Volkswagen said it was supporting the investigation and had handed over a "comprehensive" range of documents.
Later Thursday, the company's top U.S. executive Michael Horn told a panel of U.S. lawmakers he knew the carmaker might be breaking U.S. emissions rules as long as 18 months before it admitted cheating diesel tests to regulators.
Volkswagen has come under fire on both sides of the Atlantic for its handling of the crisis, with lawmakers, investors and customers saying it has been too slow to release information.
Almost three weeks after it confessed publicly to rigging U.S. emissions tests, VW is under huge pressure to identify those responsible, fix affected vehicles and clarify exactly how and where the cheating happened.
The biggest business crisis in Volkswagen's 78-year history has wiped more than a third off its share price, forced out its long-time CEO, prompted investigations across the world and rocked both the car industry and German establishment.
Analysts are still unsure how widespread the cheating was.
The automaker has previously said the software could be installed on up to 11 million vehicles, mostly in Europe, but that for the majority of them it "does not have any effect."
In a statement on Thursday, Volkswagen said it was still investigating whether or to what extent the software interfered illegally with vehicles. "We are working intensely on technical solutions," a spokesman said. "For that reason, questions posed at this point of time are speculative."
Volkswagen has suspended more than 10 senior managers, including three top engineers, as part of an internal investigation. It has also hired U.S. law firm Jones Day to conduct an external inquiry.
But some analysts have questioned whether new chairman Hans Dieter Poetsch and new CEO Matthias Mueller, both company veterans, will introduce the sweeping changes in business practices they think are necessary to restore Volkswagen's reputation.
Poetsch said on Wednesday it would take "some time" to get to the bottom of the matter.
The company, controlled by the Piech-Porsche clan, is not drawing on outside restructuring experts to help with its plans for a new company structure, one source close to the board said.
"There's a strong tradition to handle such matters in-house," the source said, adding the company was also unlikely to draw on outside experts as it reviews investment plans and steps up cost savings to help meet the cost of the scandal.
Critics say giving top jobs to company insiders could also complicate the clean-up. For example, it would make it hard for the supervisory board to take legal action against the management board because, until he became supervisory board chairman, Poetsch sat on the management board as finance chief.
UBS analysts estimate Volkswagen could face a bill of around 35 billion euros ($40 billion) to refit cars, pay regulatory fines and settle lawsuits, though they also say this is more than factored into the stock price after its plunge.
The crisis has been a major embarrassment for Germany, which has for years held up Volkswagen as a model of the country's engineering prowess and looks to the car industry as a source of export income and an employer of more than 750,000 people.
Economy Minister Sigmar Gabriel on Thursday urged Volkswagen to be pro-active in addressing its problems, but also said critics should not overstep the mark.
"There should not be a debate about the automotive industry or about diesel technology," Gabriel said after attending a meeting of Volkswagen's world workers council.
Christiaan Hetzner contributed to this report