China has dismantled over 100 underground banks and traced illicit financial transactions totaling over 80 billion yuan (about 11.1 billion U.S. dollars) amid a sweeping crackdown initiated in May.

Police nationwide have taken down 263 criminal groups engaged in illegal business operations, human trafficking, fraud, illegal detention and other related crimes, the Ministry of Public Security (MPS) said at a press conference on Friday.

Under the MPS's directive, mainland police, in collaboration with Macao law enforcement, carried out five coordinated raids, resulting in the arrest of 846 criminal suspects.

Police in Chongqing Municipality have cracked a gang that has provided money laundering and currency exchange services to gamblers in Macao since 2015. Investigations revealed that the group was involved in illegal detention, extortion and fraud, with illicit funds totaling over 84 million yuan.

In another case, police in the city of Shenyang, Liaoning Province, smashed a criminal group led by Zhang, suspected of illegal foreign exchange trading. Seventy-five suspects were arrested, and illicit funds totaling 4.1 billion yuan were seized.

Through the concerted efforts of mainland and Macao police, coupled with the criminalization of illegal money-exchange activities in Macao, such crimes have been effectively curbed, said the MPS, vowing to persist in the efforts.