German automaker Daimler said Friday it plans to invest three billion euros (4.2 billion dollars) in China by 2015 to boost production of Mercedes-Benz cars in the world's biggest auto market.

Daimler also aims to increase sales in the Asian country to 300,000 units a year in the next five years, compared with an estimated 120,000 units in 2010, global chief executive Dieter Zetsche told reporters.

"This year we originally planned to sell 100,000 units -- that has been accomplished after three quarters," said Zetsche.

"On that basis our target of 300,000 in 2015 becomes even more realistic."

Zetsche said he hoped that at least 70 percent of the 300,000 cars would be produced in China, compared with around 30 percent currently.

"We have to invest heavily to get there," he said.

Zetsche added China, where demand for high-end vehicles is growing thanks to an expanding middle class, should become Daimler's top market for Mercedes-Benz cars between 2014 and 2016, eclipsing Germany and the United States.

German groups Audi and BMW currently out-sell Daimler in China.

Audi hopes to sell more than 200,000 cars in the country this year and around 300,000 starting in 2012 or a year later.

BMW sold nearly 122,000 vehicles in China in the first nine months.