BERLIN: Record September sales in the key Chinese market boosted the global sales and market share of Volkswagen, Europe's biggest carmaker, the German firm said on Friday, as it warned of a "difficult year" ahead.

Deliveries in China in September broke all previous records with just under 150,000 units sold, a rise of 66 percent compared to last year, the company said.

This helped to push overall sales up by 12 percent last month, with the firm also improving its global market share in the first nine months of the year.

"We are continuing to steer a steady course through the crisis and are developing better the competition," said Detlef Wittig, executive vice-president of group sales and marketing.

"We have maintained our position as market leader in the important core markets of China, Brazil and Germany. At the same time, we are well placed on emerging growth markets such as Russia and India," he added.

Nevertheless, he cautioned that "2010 will be a difficult year, particularly on our core markets in Western Europe."

Volkswagen said that it had sold a total of 615,100 cars in September.

The ambitious German firm aims to overtake Toyota as the world's leading carmaker by 2018.