BEIJING -- Five Shanghai-based gold and jewelry stores and a local trade association have been fined a combined total of 10.59 million yuan ($1.72 million) for manipulating the prices of their jewelry, China's top economic planner said Monday.

The five stores are Shanghai Laofengxiang Co Ltd, Shanghai Laomiao Gold Co Ltd, First Asia Jewelry, Chenghuang Jewelry and Tianbao Longfeng, according to the National Development and Reform Commission (NDRC).

The NDRC said probes by local pricing authorities found that the five stores had manipulated the retail prices of their gold and platinum jewelry in accordance with a pricing scheme created in cooperation with the Shanghai Gold & Jewelry Trade Association.

Their practices harmed the legitimate interests of other business operators and consumers, the commission said.

According to China's anti-monopoly law, the trade association played a leading role in formulating and executing a monopoly agreement in this case and will receive a fine of 500,000 yuan, the maximum fine possible for this type of offense, the NDRC said.

The stores were fined a combined total of 10.09 million yuan, or 1 percent of their 2012 revenues, as they voluntarily corrected their illegal practices before the probe and cooperated during the investigation, according to NDRC.

The verdict marked the second anti-trust case reveale last week, as authorities have moved to clamp down on anti-competitive market conduct and clean up the country's business environment.

On Wednesday, the NDRC announced fines totaling 670 million yuan for six foreign baby formula companies operating on the mainland following an anti-trust probe, the largest such fines ever imposed for anti-trust infringement in China.

China's anti-monopoly law stipulates that fines for a company may range from 1 percent to 10 percent of its total revenues from the previous year.