Luxury carmaker Audi used software to cheat on diesel emissions tests, Germany's transport minister has said.
Alexander Dobrindt said the software used by Ingolstadt-based Audi was able to recognise when vehicles were being tested and switch on an emissions cleaning system.
Mr Dobrindt said 24,000 vehicles built between 2009 and 2013 would have to be recalled.
Munich prosecutors launched an investigation into Audi earlier this year, raiding the company's offices while executives were holding their annual news conference in March.
Parent group Volkswagen has been forced to pay out billions of dollars in fines and compensation after admitting that diesel vehicles were equipped with software to evade US limits of nitrogen oxides, a pollutant that can harm people's health.