"The drop in the number of investigations shows that the global economy is recovering and is also an indication of China's efforts to achieve balanced trade," he said.

However, trade protectionism is still increasing, he said.

For instance, the United States launched 19 cases of Section 337 investigations into Chinese imports in 2010, compared to eight investigations in 2009.

The Section 337 investigations are conducted by the US International Trade Commission, which most often involve claims relating to intellectual property rights and issues over imported goods.

"Trade barriers and trade remedy measures set or levied by the US on Chinese products have affected bilateral trade," Yao Jian, Ministry of Commerce spokesman, said at a news conference on Tuesday.

Out of the 66 trade investigations targeting China, six were launched by the US with a value of $860 million. And the US also launched 19 cases of Section 337 investigations.

Trade between China and the US was $385 billion in 2010, up 29.2 percent year-on-year. China's trade surplus with the US was $181 billion for the same period, according to the General Administration of Customs.

Yao said China's trade surplus in goods with the US should not be an excuse for barriers as the US also has a $10 billion trade surplus with China in services.

Major products that China imports from the US include soybeans, processors and aircraft, while goods that the US buys from China include computers, toys and shoes.

Long Guoqiang, a senior fellow at the research department of foreign economic relations at the Development Research Center under the State Council, said Chinese companies' technical progress is a concern behind the increasing usage of the Section 337 investigations.

"To some extent, trade friction between China and the US is due to politics, such as national security," Long said.

At the same time, national security is also a major issue that has hindered Chinese companies expanding overseas, said trade experts.

US restrictions on China's high-tech imports are "strict and extensive" and it has exacerbated trade imbalances between China and the US, Yao said.