Great Wall Motor Co, China's largest sport utility vehicle maker, has postponed its A-share listing till later this year partly due to concern over a slumping mainland stock market, a source said on Wednesday.

Great Wall, which in October 2007 announced a plan to issue up 121.7 million A shares in Shanghai, has now decided to delay its internal IPO target to September from May, said the source, who is familiar with the situation.

The source attributed the delay to China's benchmark index that is now nearly 50 percent below last October's record peak after a sixfold jump in a two year bull run.

But Great Wall would not cut the size of the share sale, valued at up to HK$1.08 billion ($138.6 million) based on its H share price on Wednesday morning, the source added.