Masayoshi Hori, executive coordinator of Toyota Motor China, said Japanes automakers won't be alone in struggling to supply the market, as the parts shortage hits brands worldwide.

"It will be global brands as well," Hori predicted on the sidelines of the Shanghai motor show. "In terms of supply, maybe will not be able to meet that demand."

Japanese automakers are just now resuming partial production in Japan, after their supply lines were shattered by the March 11 earthquake.

China's market, the world's largest, is expected to climb about 10 percent to 20 million vehicles this year, Hori said. But sales might not hit that mark.

"The China market is very firm but the future is very unclear because of the earthquake," Hori said. Toyota had expected its own sales in China to exceed 900,000 units this year, from 846,000 last year. But it is unclear if Toyota can now reach that level, he said, with plants in Japan operating after just half their normal output after nearly a month of being off line.

Toyota aims to make it up in the mid-term, however. Hori said The company aims to at least double last year's sales to as much as 1.8 million units annually in China by 2015.