Japanese automakers reported a "disastrous" decline in sales in September in the world's largest vehicle market as rising anger over Japan's illegal "purchase" of China's Diaoyu Islands kept consumers away from their showrooms.

Toyota Motor Corp said on Tuesday that its September sales in China dropped 48.9 percent year-on-year to 44,100 units, the biggest decline since January 2008.

Honda Motor Co also reported that its monthly sales dived 40.5 percent year-on-year to 33,931 units in September, the lowest figure since May 2011.

According to Dongfeng Motor Corp, the Chinese partner of Nissan Motor Co, sales of the Japanese brand's made-in-China vehicles decreased 34.6 percent from a year earlier, while Suzuki Motor Corp said its sales in China dropped 42.5 percent year-on-year.

On Friday, Mitsubishi Motors Corp announced a sales decline of 63 percent in September, while the month saw Mazda Motor Corp's China sales drop 36 percent.

"Japanese automakers and their suppliers face a tough future in China in the immediate aftermath of the protests that took place in mid-September," said Namrita Chow, senior analyst of IHS Automotive.

Toyota Motor Corp's stand at the Beijing Auto Show in April. [Photo/China Daily]

Nissan, Toyota, Suzuki and Mitsubishi had all previously been enjoying sales growth in China, but the next few months are likely to see severe declines which could seriously harm their prospects of meeting their 2012 sales targets.

The outlook for Japanese carmakers in China "does not augur well, with IHS Automotive forecasts expecting an immediate drop in sales and production amid concerns that the situation may extend for a longer period than previously thought", Chow added.

IHS Automotive currently estimates that output and sales for Japanese automakers in China will be cut by 200,000 units this year, amounting to around 20 percent of sales of Japanese branded vehicles in China.

In 2013, IHS Automotive expects a fall of around 100,000 units based on the two countries finding a peaceful resolution in the immediate future.

"Their (Japanese automakers') future depends on how quickly diplomacy can solve the situation," said Chow.

"Should the situation spiral and Japanese OEMs (Original Equipment Manufacturers) start cutting output even more, lost volumes will significantly increase."

China has been the most important market for Japanese automakers since 2005.

In 2011, Nissan's sales in China accounted for about 27 percent of its global total, while Toyota sold about 12 percent of its vehicles in China.

The world's largest automobile market also accounted for 20 percent of Honda's global sales, while the figure stood at 18 percent for Mazda.

A model stands next to a Toyota concept car Dear on June 7, 2012 at the Shenzhen-Hong Kong-Macao International Auto Show in Shenzhen. [Photo / Xinhua]