The China Automobile Dealers Association (CADA) is collecting data on the prices of all foreign cars sold in the country for the National Development and Reform Commission (NDRC), which has already fined companies for price-fixing in sectors ranging from milk powder to jewelry, officials at the industry body said.

CADA has been doing the research for the NDRC, the government's most important financial commission, since last year, said Luo Lei, deputy secretary-general of the association.

Luo said the NDRC was investigating whether carmakers were setting a minimum retail price for dealers in China, which lawyers said could contravene the country's Anti-Monopoly Law issued in 2008.

The NDRC, which is responsible for enforcing antitrust rules on pricing, declined to comment, but lawyers said it was common for the commission to seek information from industry bodies before launching a formal investigation.

Executives at foreign carmakers said they were not aware of any research being conducted by CADA, which represents car dealers across China, or an investigation by the NDRC.

Luo said the association was looking at imported cars along with vehicles produced by foreign companies in association with local partners.

"We're looking at all brands, including those imported and those made by domestic joint ventures," Luo told Reuters in a telephone interview, declining to say exactly when CADA began its research, when it might finish or why it had taken so long.

"We see there's a big difference in the prices of imported cars in China and their overseas prices. We're looking into that," Luo said.

Another CADA official, who declined to be identified because she was not allowed to speak to the media, said the association was collecting data on the overseas and domestic prices of different brands of cars as well as information on profit margins, costs for carmakers and various taxes levied on vehicles.

The Xinhua News Agency said in an editorial in late July that foreign carmakers were reaping exorbitant profits through selling imported luxury cars in China and should face an antitrust investigation.

It said some imported cars were twice as expensive in China than in overseas markets. Among those it singled out were Volkswagen's luxury division Audi and BMW.

BMW's office in China declined to comment on any possible NDRC investigation. Audi's office in the country did not respond to a request for comment.