Police in China have intensified efforts to crack down on underground banks to prevent suspected corrupt officials from transferring their ill-gotten assets abroad through money laundering.

Crimes related to underground banks have become increasingly severe and complex, according to a senior Ministry of Public Security official.

Apart from some of the worst-hit places, such as Guangdong province, such crimes have spread to other areas of the country, Meng Qingfeng, vice-minister of public security, told China Daily.

These crimes not only involve financial and securities offenses, but have also become an underground route and method of money laundering for many suspected corrupt officials and terrorist suspects to illegally transfer their money overseas, he said.

"A large number of ill-gotten gains flowing in and out of China through underground banks have had a serious impact on foreign exchange management and seriously disturbed order in the financial capital market, posing a serious threat to financial security," Meng said.

In recent years, many suspected corrupt officials have fled overseas to escape punishment.

The United States, Canada, Australia and Singapore are among the popular destinations for fugitives due to a lack of extradition treaties and legal differences between China and these countries, according to the ministry.

A number of suspected corrupt officials, mostly government employees or senior managers of State-owned enterprises, have illegally transferred millions of dollars overseas through money laundering at underground banks, the ministry said.

Since April, the ministry has worked closely with the People's Bank of China－the central bank－and the State Administration of Foreign Exchange to monitor the suspicious flow of funds sent to foreign accounts.

The ministry has also tightened supervision of offshore companies and targeted underground banks to prevent suspects from sending proceeds abroad.

From the end of August to the end of September, police smashed 37 underground banks and captured 75 suspects. They have also uncovered dozens of major cases involving a total of 240 billion yuan ($37.8 billion).

"Cracking down on underground banks is an issue closely related to national economic safety, as well as overall economic and social development," Meng said.

He added that the ministry launched a three-month special campaign at the end of August to target underground banks and money laundering crimes.

During this period, it will step up cooperation with the People's Bank of China and the State Administration of Foreign Exchange to share and analyze evidence and set up a system to carry out rapid checks on suspicious asset flows, he said.

Special police will also investigate major underground bank crimes and clues involving other economic crimes, Meng said.

They will regularly publicize these crimes and the danger they pose to the public.

Zhang Xiaoming, deputy direct-or-general of the ministry's Legal Assistance and Foreign Affairs Department, said financial intelligence exchanges with the US and Australia will be strengthened to trace and confiscate illegally acquired assets transferred by suspected corrupt officials.

A source at the People's Bank of China said the bank is in discussions with the US Financial Crimes Enforcement Network, a bureau under the US Treasury that monitors financial transactions to com-bat such crimes.

A bilateral agreement will be signed to target suspicious assets transferred overseas by suspected corrupt Chinese officials.

The central bank will sign a similar agreement with the Australian Financial Intelligence Unit to monitor the flow of such assets, the source said.