Prosecutors allege ex-VW boss learned of diesel cheating by 2014

Prosecutors have alleged that former Volkswagen boss Martin Winterkorn knew about a scheme to manipulate emissions tests on VW diesel engines far earlier than he has acknowledged, reported dpa.

Winterkorn's criminal trial over his alleged role in the so-called "Dieselgate" scandal at Volkswagen began on Tuesday in the German city of Braunschweig.

In the indictment, prosecutors said that Winterkorn knew by May 2014 at the absolute latest that the automaker was using illegal software to evade emissions rules in the United States.

An investigation by US regulators uncovered the illegal software in September 2015, unleashing a scandal that cost Volkswagen billions and badly damaged the company's reputation.

After May 2014, Winterkorn "failed in breach of duty" to stop the sale of affected cars, prosecutors said. They estimated that Winterkorn's inaction resulted in the sale of more than 65,000 illegally manipulated diesel vehicles and caused damage of around €1.3 billion.

Winterkorn, 77, faces charges of commercial fraud, market manipulation and making false statements. On Tuesday, his defence attorney denied all the allegations and said the former executive is innocent.