Kia Motors has delayed commercial production at its second plant in China, scheduled to be started this month, amid sluggish demand in its second-biggest export market.

Kia has completed building the $US600m plant with its two Chinese partners at Yancheong in the eastern province of Jiangsu, but commercial production at the plant was delayed for "several months to add some facilities," Kang Hyun-geun, a company spokesman, told the Yonhap news agency.

"No exact date has been set for commercial production," Kang was quoted as saying.

Last month, parent company Hyundai cut its sales target for China by 16% to 260,000 vehicles, citing weakening demand, the report noted.

On Sunday, Hyundai Motor chairman Chung Mong-koo told reporters that Kia has delayed commercial production at the plant until January next year.

Kia's two Chinese partners - Dongfeng Motor and Jiangsu Yueda - are "strongly opposing" the delay, Chung was quoted as saying by the Seoul Economic Daily.

However, the Kia spokesman denied any friction with the Chinese partners, Yonhap added.