Beijing, China (CNN) -- More than 6,000 people were detained for crimes such as theft and prostitution during a recent 12-day police crackdown in Shanghai, Chinese media reported.
The police sting was aimed at making the streets safe in preparation for the World Expo in Shanghai, China Daily newspaper reported.
More than 30,000 police officers were used in the operation that went from April 3 to 14, the paper reported. Of the 6,402 detained, 429 are now under criminal detention, a designation that could lead to formal arrests and prosecution, the newspaper reported.
Those suspects had been accused of offenses including gambling, prostitution, theft and selling pornographic materials. Also 852 people were being held under administrative detention, a designation that could lead to a maximum term of 15 days in jail.
"The others were released after being educated," China Daily reported.
The crackdown occurred near the were the event will occur in Shanghai.
Organizers say the World Expo in Shanghai, a world's fair-type exposition that opens May 1, will draw more than 100 million people during its six-month run. About 190 countries are taking part in the event.