A high-ranking Foreign Ministry official says the United States will soon explain why it imposed financial sanctions on North Korea.

Kim Sook, director general at the ministry's North American affairs bureau, told a KBS radio program Thursday that Washington says the sanctions are a defensive and not offensive measure, and that it will probably not connect the move with the six-party nuclear talks.

He said the United States has investigated for years the North's illegal activities such as counterfeiting, and closely consulted Seoul on the matter.

Kim also denied that recent blasts by American officials against the North imply a change to a policy of pressure towards Pyongyang.