REUTERS - Volkswagen Group’s (VOWG_p.DE) Chief Executive Herbert Diess warned that new anti-pollution tests pose a risk to the carmaker’s profit targets.

VW has warned that production of up to 250,000 cars will be delayed as it struggles to adapt its vehicles to a new anti-pollution test, the Worldwide Harmonized Light Duty Vehicles Test Procedure (WLTP).

In a press conference on Wednesday to discuss second-quarter results, Diess said the ongoing changeover to the WLTP test procedure poses, “The biggest volume and earnings risk for Volkswagen.”