The Bank of China has severed business with North Korea's main foreign exchange bank which is said to have ties with the North’s nuclear weapons development.

A spokesman for the Chinese bank said Tuesday that it notified the Foreign Trade Bank of the DPRK that its accounts have been closed. The BOC also halted all fund transfers related to the North Korean accounts.

The spokesman did not elaborate on the number of North Korean accounts it has shut down.

The move follows U.S. Treasury Undersecretary for Terrorism and Financial Intelligence David Cohen's visit to China last month, during which he asked for Beijing's active support in sanctioning Pyongyang.