QINGDAO, Shandong - Fourteen police officers, including two police bureau chiefs, who are accused of involvement in a large criminal gang case in East China's Shandong province, have been placed under investigation.

In addition, police said they have smashed a mafia-style gang that had more than 200 members. The gang leader, 44-year-old Nie Lei, was among those detained, police said at a news conference in the Qingdao public security bureau on Friday.

The gang members are accused of organizing illegal gangs, deliberately causing injury, organizing trade in sex, gambling and illegal gun trading.

Last year, some of the gang members are alleged to have attacked a nightclub in a hotel in Qingdao, injuring many people.

After a year-long investigation, police said they smashed the gang in June 2010.

A task force of 360 police officers from various local public safety agencies conducted investigations that led to the arrest of Nie Lei, 44, the alleged gang leader.

Nie, a Qingdao resident, has twice been imprisoned for robbery and has been sentenced to time in a labor camp.

He is accused of extorting protection fees from local night clubs and then investing in real estate. He reportedly once had a mansion near Qingdao Railway Station.

Nie's gang was described as the biggest mafia-style organization to exist in Qingdao since the founding of the People's Republic of China in 1949.

Yu Guoming, head of Shibei sub-bureau of the Qingdao public security bureau, and Feng Yuexin, head of the Licang sub-bureau, are accused of providing shelters for the gang.

"(These) have severely tarnished the image and credibility of the police in Qingdao," said a statement issued by Qingdao Public Security Bureau.

"The Qingdao government is now intensifying efforts to fight organized crime to better protect the basic rights of Qingdao's citizens," an unidentified officer said.

Wu Binbin contributed to this story.