China's auto sales slumped by 17.4 percent in June from May, to less than 10 million vehicles, while production of autos also dipped by about 11 percent. Car sales have been on the decline for two consecutive months in China, as auto warehousing has been on the rise, eating into manufacturers' profits.

Overall auto sales in the United States were also down from May, raising questions about whether the industry and investors overestimated the strength of what is shaping up as a very limited recovery from the depressed 2009 levels.

"June came in fairly anemic," said Al Castignetti, who heads Nissan brand sales in the United States.

On the annualized basis tracked by analysts and investors, U.S. auto sales slipped to 11.08 million vehicles in June, down from 11.6 million in May and below the 11.15 million average of the first half, according to industry tracking firm Autodata.

Some analysts had expected 2010 U.S. auto sales to rebound as high as 12.5 million vehicles, up from the 10.6 million sales recorded in 2009. But the high end of that full-year sales forecast now appears out of reach, executives said.

The lower-than-expected U.S. sales come as weaker sales in France and the prospect of higher taxes in markets like Spain deepened concern about a double-dip recession worldwide.