Authorities have pledged to work together to intensify the crackdown on illegal underground banks to maintain financial order and security, Economic Information Daily reported.

Police in the northeastern city of Qitaihe, Heilongjiang province, have successfully busted an underground banking network that handled hundreds of billions of yuan worth of illegal transactions. The case involved eight underground banks and more than 80 suspects were arrested.

Shu Jianping, head of the anti-money laundering office of the economic crime investigation division of the Ministry of Public Security, said that the Qitaihe case showed that criminals are upgrading their methods and spreading to inland regions from coastal areas.

Cases related to underground banks affect several industries, including foreign trade and real estates, Shu added.

"Underground banks have been a quick way to transfer money for a long time, for they are anonymous and hidden. Many criminals have taken advantage of the channel to transfer their illegal gains to abroad," said Zhang Niannian, an official with the central bank, the People's Bank of China.

The central bank will track and analyze new methods of crimes, especially in non-financial institutions and sectors, and improve anti-money laundering measures, Zhang said.

The Ministry of Public Security will continue to act against illegal underground banks in cooperation with the central bank and the State Administration of Foreign Exchange this year, the newspaper added.

Xinhua contributed to this story.