BEIJING - Chinese customs authorities have put 834 criminal smuggling cases on file for investigation in the first five months of the year.

The cases involve 15.5 billion yuan (2.5 billion US dollars), the General Administration of Customs said Wednesday. Of the total, 31 major cases each involve tax evasion totaling more than 10 million yuan.

During the five-month period, the administration also ferreted out 6,654 smuggling cases involving 2 billion yuan that are punishable by customs law, as well as 31,025 cases of minor customs violations with a value of 18.7 billion yuan.

The administration also intensified a crackdown on the smuggling of mineral resources like rare earth and graphite, uncovering 26 cases worth 260 million yuan.

In 2012, the government investigated 1,832 criminal smuggling cases with a value of 34.3 billion yuan.