BEIJING - Chinese officials have expressed their regret that the World Trade Organization (WTO) has upheld its ruling against China in a raw materials export case, the Ministry of Commerce (MOC) said Tuesday.

China welcomed the WTO's support for China's appeal on major issues in the case, under a process which allows the ruling body to correct some false judgements. But, at the same time, it is regretful that the ruling has been upheld, the ministry said in a statement on its website.

In 2009, the United States, the European Union and Mexico filed a complaint to the WTO, claiming China's export restrictions on nine raw materials, including zinc, coke and magnesium, inflated global prices and gave an unfair advantage to the country's domestic producers.

China contended that the restrictions were placed on the materials on the basis of protecting the environment and exhaustible resources.

Last July, the WTO ruled that China's export quota broke trade rules. China filed a complaint two months later, requesting part of the ruling be canceled.

In the statement on the MOC's website, an official with the legal and treaty department of the ministry reiterated that China has tightened administration over energy-consuming and highly polluting resources in recent years.

"The WTO should not only uphold free trade but also allow members to take necessary steps to protect the environment and natural resources," according to the statement.

In a bid to realize sustainable development, China will carefully evaluate the WTO's ruling and continue to enhance the scientific administration of resource products based on WTO rules, it said.

The MOC has made preparations for possible complaints about other resource products, including rare earths, an anonymous official with the ministry told Xinhua on Tuesday.