Police in Changsha, capital of Central China's Hunan province, arrested 15 gangs with 3,000 suspects following a crackdown on such crimes in the city since September.

These gangs, referred as "underground police" by local people, were mostly made up of jobless young people. They were often hired to commit crimes for their employers' economic interests, like fighting for territories and construction projects and solving disputes by violence, China Central Television reported.

According to local police, the expansion of such gangs in Changsha is due to more people resorting to extreme methods to solve business disputes in the rapid economic and social development.