The state-owned Bank of China has shut the account of a North Korean bank the US accuses of backing Pyongyang's nuclear program, Dow Jones said Tuesday, citing a statement from the Chinese financial institution.

Beijing is Pyongyang's key backer and it would be the first openly acknowledged move by a Chinese institution against North Korean interests in the current stand-off, which escalated in February with Pyongyang's third atomic test.

"The Foreign Trade Bank of North Korea, the country's main foreign-exchange bank, has been told its account has been closed," Dow Jones reported.

The Bank of China is one of the biggest state-owned banks in the country and is subject to political directives from the Chinese authorities.

Washington imposed sanctions on the North Korean organization, Pyongyang's primary foreign-exchange bank, after the latest nuclear blast.

It has urged China -- which provides the North with key energy, trade and aid -- to do more to contain its smaller neighbor. There have also been domestic calls for China to reduce its closeness to North Korea.

Beijing has supported separate United Nations sanctions, which were also expanded after the February test.

But it has also said sanctions are not the "fundamental way" to resolve the crisis, and has tended to avoid antagonizing Pyongyang for fear of provoking an over-reaction and destabilizing the region.

Dow Jones said the bank did not provide further details in its statement and declined to provide additional comment. (AFP)