A Volkswagen engineer warned the company about cheating over its emission tests as early as 2011, a German newspaper reports.

Frankfurter Allgemeine Sonntagszeitung says the warning emerged during VW's current investigation into the scandal.

Separately, Bild am Sonntag said the internal inquiry had found that parts supplier Bosch had warned Volkswagen not to use its software illegally.

Volkswagen told the BBC they would not comment on "newspaper speculation".

Last week VW apologised for cheating on emissions tests in the US. Some 11 million VW diesel cars built since 2008 are affected by the scandal.

They had devices which could detect when the engine was being tested and could change the car's performance to improve results.


Volkswagen: The scandal explained

Citing unidentified sources, Bild said Bosch had warned Volkswagen as early as 2007 that its software should only be used in company tests and not for normal driving.

Last week VW's chief executive Martin Winterkorn was forced out over the scandal and replaced by Matthias Mueller, the former head of Porsche.

VW is a brand and in a class of its own... Why cut corners?... I still respect them though