China has started investigation procedures on auto and chicken products originally produced in the United States, Yao Jian, spokesman with the Ministry of Commerce (MOC), told a press conference on Tuesday,  adding to a string of trade disputes with Washington including a recent decision to raise tariffs on Chinese-made tires.

The MOC will follow relevant regulations to carry out related work, Xinhua reported, citing Yao as saying.

The ministry said on Sunday domestic enterprises had complained chicken and auto products from the United States were allegedly entering the Chinese market through unfair trade involving dumping and subsidy.

Domestic enterprises said the alleged dumping had hit the domestic market and asked the ministry to investigate, the ministry said.

Washington and Beijing have recently traded accusations of protectionism, which they agree will hurt efforts to end the global economic crisis.

The U.S. and China, the world's largest and third-largest economies, have been engaged in a series of battles over access to each other's markets for goods such as tires, steel pipe, music and movies.

President Barack Obama on Friday approved new tariffs on all car and light truck tires coming into the U.S. from China, a move Beijing condemned as protectionist and a violation of global trade rules.

China is strongly opposing trade protectionism and is willing to cooperate with other countries to promote the global economic recovery, the Commerce Ministry's statement said.

The World Trade Organization (WTO) launched an investigation of the U.S. ban on Chinese poultry at the end of July. China told the WTO's dispute settlement body that U.S. had imposed protectionist measures in completely banning Chinese chicken products entering the U.S. market. The United States said it was still examining whether Chinese poultry was safe for human consumption.

Last month, China said it revised its tariffs on imported auto parts after losing an appeal of a WTO ruling against its policy of requiring foreign automakers to buy more than 40% of the components used in any China-made vehicle from local suppliers or pay more than double the usual tariff on imported parts.

According to Beijing's revision,  all imported auto parts will be taxed at the same rate regardless of the percentage of foreign-made parts used to make a vehicle.

Higher tariffs were needed to prevent automakers from evading steep vehicle import duties by importing cars in large chunks, China said. The U.S., the 27-nation EU and Canada contended that the tariffs encouraged car parts companies to shift production to China, costing Americans, Canadians and Europeans their jobs.