KUNMING, Jan. 8 (Xinhua) -- Police in southwest China's Yunnan Province have confiscated more than 30 tonnes of frozen chicken feet smuggled to China.

Four suspects were detained. Police also confiscated four vehicles. The frozen products were transported into the country from Vietnam, according to the public security bureau of Maguan County, where the case was busted. The suspects planned to transport the chicken feet to the provincial capital Kunming, as well as other areas in the country.

Further investigation is underway.

It is not the first time chicken feet have been the center of public clamor. In 2013, police in neighboring Guangxi Zhuang Autonomous Region confiscated more than 20 tonnes of chicken feet from a frozen meat warehouse, some of which were more than 40 years old.

Cooked chicken feet, often served as a cold dish, are popular in China. With supply hardly keeping pace with demand, chicken feet are being illegally imported, processed locally, and sold to vendors across China.

Frozen products like chicken feet may contain viruses and be a hazard to public health.