Herbert Diess, CEO of the Volkswagen stock company, poses for the media prior to a press conference in Wolfsburg, Germany, Wednesday, Aug. 1, 2018. (AP Photo/Michael Sohn)
INTERNATIONAL - VW chief executive Herbert Diess was given a memorandum warning the car manufacturer might face legal action in the US over the use of cheating software in cars just days before the scandal broke, a public broadcaster reported on Friday.

A former Volkswagen employee told the Braunschweig public prosecutor’s office that he wrote a so-called “one-pager” on September 13, 2015, saying that Volkswagen had lost all credibility with US authorities and was about to be charged, German public broadcaster NDR reported.

The employee further testified that he gave the document to Diess in person on September 14, 2015, NDR said. US regulators exposed VW’s cheating on September 18, 2015.

Volkswagen has said the scandal has cost it more than $27billion (R384bn) in penalties and fines.

Volkswagen’s senior management, which has denied wrongdoing, is being investigated by prosecutors in Braunschweig, near where Volkswagen is headquartered, to see whether the company violated disclosure rules.

Diess, who was VW's brand chief at the time, became chief executive of Volkswagen Group in April this year.

The Braunschweig prosecutor’s office was not immediately available for comment on Friday. A spokesperson for Volkswagen said in emailed comments that the group was only recently given access to documents in the case, adding this had so far not led to new findings. He added that it was inappropriate to use individual statements from the files and to comment on those, adding Diess, Volkswagen supervisory board chairperson Hans Dieter Poetsch and former Volkswagen chief executive Martin Winterkorn would not comment in light of the ongoing investigation.

German magazine Der Spiegel last week reported that Diess was present at a meeting on July 27, 2015, when senior engineers and executives discussed how to deal with US regulators, who were threatening to ban VW cars because of excessive pollution levels.

In a defence document filed with the Braunschweig court in February, Volkswagen said that Poetsch, who was VW’s chief financial officer at the time, on September 14, 2015, believed the potential financial risk from regulatory penalties tied to emissions would be about $172million.

VW said in its legal defence document that because the internal estimate was so small, VW felt potential costs could be covered by already accrued legal provisions.