NANNING, Nov. 6 (Xinhua) -- Chinese customs has seized more than 7,000 tonnes of frozen food worth more than 210 million yuan (30.3 million U.S. dollars), Nanning Customs in southwest China's Guangxi Zhuang Autonomous Region announced on Tuesday.

Twenty-nine suspects of six smuggling gangs were caught during the joint operation of customs officers in Nanning, Changsha and Zhengzhou cities.

The investigation shows that since February, the smuggling gangs ordered large amounts of frozen food including frozen chicken feet and frozen beef from foreign countries.

Smuggling affects domestic food production, leads to tax evasion and poses serious food safety hazards.