Growth in China's auto sales slowed in May from a double-digit rise in April, an industry group said, as new data fuelled concerns that the world's second-biggest economy is faltering.

The country's vehicle sales rose 9.8 percent year-on-year last month to 1.76 million units, the China Association of Automobile Manufacturers said.

In April, vehicle sales in China -- the world's largest auto market -- had surged 13.4 percent on the year.

Several May economic figures released over the weekend have raised concern over the outlook for China's economy, which grew 7.8 percent in 2012, its worst performance in 13 years.

Auto sales for the first five months of the year fared better, rising 12.6 percent year-on-year to 9.03 million vehicles, the association said in a statement on Sunday.

"In the first half of the year, auto production and sales will continue to maintain a more than 10 percent increase, generally better than forecast at the beginning of the year," it said.

China's auto sales rose only 4.3 percent annually to 19.31 million units in 2012, hit by limits on numbers imposed by some cities to ease traffic congestion and tackle pollution.

Since last year, sales of Japanese brand vehicles have suffered from a territorial row between Beijing and Tokyo that sparked street protests and boycott calls, but other foreign auto manufacturers have rushed to gain market share.

Sales of Japanese brand passenger cars fell 11.5 percent year-on-year in the first five months, the official Xinhua news agency reported.

But sales of German, American, South Korean and French passenger cars all grew more than 20 percent in the period, it said, quoting the association.