Despite this, the issue "did not receive particular attention."
Volkswagen has admitted that its former CEO Martin Winterkorn was told of the company's issues with diesel emissions tests in the US.
The German car manufacturer made the admission on the first day of what will be a year-long European Parliamnent investigation into how the September 2015 scandal over cheating emissions testscould have been prevented.
Despite Winterkorn receiving a memo in May 2014 about a study raising questions over the disparity between the real-world smog levels his company's diesel vehicles were responsible for and results from government tests, Volkswagen say the problem "did not initially receive particular attention at the management levels."
It was noted that the memo was part of the then-CEO's "extensive weekend mail" and that "whether and to which extent Mr Winterkorn took notice of this memo at that time is not documented."
The sender was not revealed.
In November 2014, Winterkorn was privy to another memo concerning a cost framework for the issue. He was also at a meeting the following July at which the topic of diesel emissions was raised. His knowledge of any cheating on tests is not known.
That public revelation that software been employed in 11 million cars worldwide to trick tests forced Winterkorn's resignation last September and prompted global lawsuits and the current investigation.
Writing on its website on Wednesday, Volkswagen says it intends to defend itself against legal actions from shareholders.
The company will also have to deal with a class-action lawsuit in the US concerning damages to both car owners and the environment.
Legal costs and potential fines could cost the motoring giant tens of billions of euros.
The law firm Jones Day is to publish a report investigating those responsible, on behalf of Volkswagen, next month.