The German automobile manufacturer Volkswagen says that the scandal over falsified US vehicle emission tests could affect 11 million of its cars worldwide. This comes as the number of investigations of its diesel models continue to increase, mounting further pressure on CEO Martin Winterkorn. According to several media outlets, the US Department of Justice is now opening an investigation after the world's leading car seller apologised for using software to manipulate emission tests. Volkswagen shares fell in Tuesday trading in Frankfurt, after slumping nearly 20% on Monday. The company was forced to recall half a million vehicles earlier this week. Meanwhile, South Korea is launching an investigation into whether Volkswagen cheated emissions tests in the country while France's Finance Minister is calling for an EU investigation.