A man who led a criminal gang that conducted a nine-year reign of terror over a county in southwest China was jailed for 20 years on Wednesday.

The Chongqing No. 3 Intermediate People's Court convicted Ran Guangguo of running a criminal gang, and sentenced seven members of the gang to jail terms ranging from two to 12 years at the first instance trial.

The court heard that Ran and his gang used violence to expel two smaller gangs from Baima Township, Wulong, in 2004.

He then became a loanshark, opened underground casinos in local tea houses and hired strongmen. The gang seriously disrupted social order in Wulong, the court heard.

Chongqing started a massive crackdown on organized crime in June, exposing deep ties between police and criminals.

A spokesman for the municipal procuratorate said police had arrested 700 people in connection with gang-related crimes in Chongqing in the year till November.

At least 50 others, including 28 judicial and police officers, had been investigated on suspicion of power abuse, including allegations of corruption, malfeasance and infringing people's rights, he said.