STOCKHOLM: Sweden's anti-corruption prosecutor announced on Tuesday the opening of an ‘aggravated fraud’ investigation against German automaker Volkswagen, which has acknowledged rigging its vehicles for environmental emissions tests. The investigation will examine diesel models imported to Sweden between 2009 and 2015. These models were equipped with software that minimised emissions during pollution tests, but allowed the vehicles to spew out far more nitrogen oxide while on the road. In September, the group had indicated about 225,000 such cars had been imported to Sweden, including about 104,000 cars of the Volkswagen brand, 57,000 Audis, 28,000 Skodas, 2,000 Seats and 33,000 Volkswagen trucks.