Some 6,500 cases of commercial bribery, involving 1.1 billion yuan (160 million U.S. dollars), were investigated by Chinese police in the last five years, according to the Ministry of Public Security.

Over 5,000 people involved in these cases were penalized, according to a statement released Sunday from the ministry's workshop on combating commercial bribery held in central Chinese city of Changsha.

According to the statement, the ministry has launched a crackdown, focusing on sectors most prone to commercial bribery, including construction, real estate, finance, logistics, hospitals and education.

The ministry plans to step up efforts in investigating commercial bribery cases and collecting information so as to discover more of such cases.