Recent anti-Japanese protests haven't hurt Japanese automakers' sales in China, but companies are wary of problems if the unrest continues, executives told the Associated Press (AP) on Thursday.

Japan's top car makers were reported to have stuck to plans to attend Shanghai's motor show, which opens Friday, despite demonstrations in Shanghai last weekend in which protesters laid siege to the Japanese Consulate and vandalised at least 14 Japanese-related businesses.

AP noted that some Japanese model cars also were overturned and damaged during the demonstrations, which drew crowds of 20,000 people, many of them university students - the rancour has threatened to harm economic ties amid widespread calls for boycotts of Japanese products.

But it hasn't affected car sales so far, executives at Toyota, Nissan Motor, Mitsubishi, Honda and Mazda told the news agency.

"As of last week, orders were running above average and for the past two months they have been double our average," Stephen Odell, Mazda Motor Corp.'s marketing director told AP, adding: "Read into that what you will."

Atsuyoshi Hyogo, chairman and president of Honda Motor (China) Investment Co., reportedly was even more emphatic: "There have been no problems so far. Nothing so far."

The Associated Press said that, despite ever closer economic ties, friction over World War II history and other issues has sunk relations between Beijing and Tokyo to their lowest level in decades - Honda's president announced earlier this month that his company was cutting back on business trips to China and taking other precautions while executives at other companies said they were sticking to their original plans, but paying more attention to safety.

"Everything is just as we intended. There is no change at all," said Katsuyuki Suginohara, Toyota's general manager for corporate communications, but, he reportedly added: "Naturally, we told everybody participating to be careful."

Asked by the news agency if the protests were raising the risks of doing business in China, Katsumi Nakamura, president of Nissan's joint venture with Dongfeng Motor, said the company was "studying the issue very carefully."

"The relations between Chinese and Japanese are very important and are essential for the future of the two countries," Nakamura told AP, adding: "We hope for a resolution (of the dispute) as soon as possible."

Though upbeat about the growth potential for the Chinese market, Japanese attending the show reportedly said they were showing "restraint" when outside the motor show.

"The Japanese visitors aren't going sightseeing like they usually would. They're keeping a very low profile," Chikashi Yoneyama, a Tokyo-based designer at Sivax Inc., which is showing two of its concept cars at the show - the Kira and the X-Tile - told the Associated Press.

With hundreds of millions of dollars in investments in the Chinese mainland, the car company officials reportedly said they were determined to move ahead with expansion plans that are crucial to maintaining their global competitiveness.

"Mazda is an international business and we work with good partners," Odell told the Associated Press, adding: "We don't make those investments lightly."