No North Korean banks are believed to be operating in China, but there are some unauthorized North Korean financial entities that help illegal money flow into the North, multiple banking sources in Beijing said Tuesday. 

The U.N. Security Council adopted a package of tougher sanctions last week against North Korea's fourth nuclear test and rocket launch. Under the measures, countries are required to freeze the assets of North Korean financial institutions and other entities linked to the North's nuclear and missile programs. 

The banking sources in Beijing said there are no North Korean banks operating in China under Chinese regulatory approval.

"To my knowledge, there are no North Korean banks doing normal financial transactions in China," a banking source said on the condition of anonymity.

In the northeastern Chinese border city of Dandong, where nearly 70 percent of bilateral trade between North Korea and China is being conducted, a branch of the North's Korea Kwangson Banking Corp. is reportedly doing business. 

However, such a North Korean financial entity is not authorized by China's banking regulator, another source said. 

Despite the absence of official banking transactions, money continues to flow into North Korea via couriers carrying cash, the second source said. 

In 2005, North Korea was hit by U.S.-led financial sanctions that froze $24 million in assets in Banco Delta Asia in Macao. 

Since then, North Korea is believed to have developed various ways to evade international financial restrictions. (Yonhap)