China on Monday formally requested the World Trade Organization (WTO) to set up an expert panel to investigate and rule whether a U.S. ban on Chinese poultry imports violates WTO regulations.

The request was made at a meeting of the WTO's Dispute Settlement Body, but it was rejected by the United States according to relevant procedures.

During the meeting, the Chinese delegation reiterated that the U.S. measure is "discriminatory" and "has damaged the lawful rights and interests of China's poultry industry."

"While violating various WTO rules, the measure has severely undermined the stable development of Sino-U.S. trade in poultry products," the Chinese delegation said.

At the heart of the dispute is the U.S. Omnibus Appropriations Act of 2009, which contains a section prohibiting any funds being used to facilitate imports of poultry products from China. The act was signed into U.S. law in March, and China filed complaints to the WTO in on April 17.

While Monday's request for the WTO panel was rejected by the United States, China could make a second request at the end of this month. After the second request, the WTO panel will be established automatically.

It usually takes more than half a year for a WTO panel to give its final ruling on a trade dispute.

China and the United States banned imports of each other's poultry products in 2004 following outbreaks of bird flu. They agreed to lift the bans at the Sino-U.S. Joint Commission on Commerce and Trade in 2004.

China did lift the ban but has complained that the United States was not following suit.

China imported 580,000 tons of chicken products from the United States last year, accounting for about 75 percent of total chicken imports.