The Ministry of Public Security will greatly enlarge a special division dealing with gang-related crime amid a nationwide sweep, a senior official has said.

"To better tackle mafia-style gangs across the country, the organized crime investigation division will be expanded to include three task forces," Huang Zuyue, deputy director of the ministry's criminal investigation bureau, said during an online interview on the ministry's website over the weekend.

Huang said the three task forces would be made up of 26 officers, compared with the existing six.

Provincial- and city-level police authorities are also trying to set up special forces to tackle gangs, Huang said.

"These special forces will keep a close watch on gang-related crime, just as cats watch mice," he said.

Unlike local officers who directly handle gang-related crimes, those on the special task forces will generally be responsible for supervision and information sorting, experts said.

Although the ministry said a national crackdown has been continuing since 2006, the campaign had not received much public attention until last year when Chongqing municipality launched a high-profile crime sweep.

The Chongqing campaign is in the spotlight not only because of its unprecedented action against gangsters but also corrupt officials.

Figures from the Chongqing procuratorate show that last year, 12 bureau-level officials - one level lower than ministerial officials - were investigated for engaging in gang-related crime or protecting gangsters.

Huang made it clear that it is not only Chongqing which is fighting gangs. Since 2006, 1,304 mafia-style gangs and 14,590 less-organized groups have been smashed across the country. More than 90,000 suspects were rounded up and as many as 100,000 crimes cracked, he said.

Tong Bishan, director of the ministry's organized crime investigation division, has said the fight would be a "lasting task".

"In the foreseeable future, gangs will remain active as the country undergoes dramatic social and economic changes," he told China Daily in an earlier interview.

Increasing social conflicts as well as the widening gap between the rich and the poor are also reasons behind gang crimes, Liang Huaren, a professor in criminal law at China University of Political Science and Law, has said.

Huang said gangs based at markets and bus/train traffic stations, as well as new types of gang-related crimes such as illegal debt collection and "underground policing" will be a major target in crackdowns, he said.

Huang also encouraged the public to offer tips to police. He said last year, the bureau had received 979 major clues from the public for investigations, which "greatly helped police work".

However, the ongoing crackdown on gangsters has also triggered worries that it could turn into a "movement" in which the rights of suspects and their lawyers could be harmed.

Such concerns reached a peak after a Beijing lawyer received two-and-half years in jail on Friday in Chongqing for fabricating evidence and interfering with witness testimonies while defending a suspected gang leader.

Huang did not mention the case in his one-hour online discussion.

Meanwhile, in another high-profile fight against human trafficking, police across the country had rescued 3,455 children and 7,365 women from April to the end of December last year, he said. A total of 1,684 human-trafficking groups were smashed and 2,895 cases were solved.