GUANGZHOU -- Police from south China's Guangdong Province, Hong Kong and Macao have jointly broken up 1,400 gangs, cracked 10,942 criminal cases and nabbed 24,860 suspects in a sweeping crackdown on organized crime which ended the week before the 10th anniversary of Hong Kong's return to China.

The 50-day-long "Thunderbolt 07" operation, launched from early May to June 24, focused on closing down online gambling, loan sharking, cross-border prostitution and drug dealing, as well as other types of crimes, said a spokesman with the Guangdong Provincial Department of Public Security on Wednesday.

Twelve of those arrested were wanted by police in Hong Kong, Macao and Taiwan. Another is a member of Hong Kong's notorious 14K Triad. Six others are from other countries, the spokesman said.

Police confiscated 159 guns, 580 rounds of ammunition, 30 kg of heroin, 400 kg of crystal methamphetamine commonly known as "ice", 300 kg of ketamine commonly known as "K" and more than 9,000 motor vehicles, he said.

"The crackdown aims to maintain social stability in Guangdong, Hong Kong and Macao, and to ensure a peaceful environment for the celebrations for the 10th anniversary of Hong Kong's return to the motherland," the spokesman said.

Chinese President Hu Jintao will visit Hong Kong from June 29 to July 1 to attend anniversary celebrations and the inauguration of the third-term Hong Kong Special Administrative Region Government.