Sydney - The Australian unit of German carmaker Volkswagen AG said it will conduct a voluntary recall of vehicles fitted with devices designed to mask the level of emissions, as it increased the estimated number of affected cars to nearly 100,000.

Volkswagen Group Australia on Friday said its head office in Germany had identified another 6,444 cars, two days after it put the total figure at 90,000.

Although the Australian unit gave no timetable, the recall pulls it in line with head office plans to start recalling up to 11 million vehicles globally in January, following revelations they were fitted with illegal software.

The biggest crisis in Volkswagen's 78-year history has wiped more than a third off its share price, forced out its longtime chief executive and sent shockwaves through both the global car industry and the German establishment.

Australian regulators have already launched an inquiry to decide if consumers were misled, while law firm Maurice Blackburn has said it is considering filing a class action suit to compensate customers for lost re-sale prices.

The Australian Volkswagen unit said it would write to all affected car owners about the recall. It has also set up a website for customers to see if their vehicles, including more than 60,000 Volkswagen branded passenger cars, 5,000 Skodas and more than 17,000 Volkswagen commercial vehicles, have the affected EA 189 diesel engines.