The exchange rate of the North Korean won against the Chinese yuan has plunged to the 800 won range one week after surging over one thousand won.

A source close to the North's foreign exchange market said Friday that the won-yuan exchange rate is around 780 to 800 won in Hyesan region and over 800 won in Cheongjin in North Korea. The source said the rate reached one thousand won just a week ago, but now it's suddenly plunging. A falling rate means a higher appreciation of the North Korean currency which is highly unusual.

The source cited a rumor that counterfeit North Korean bills were released in mass amounts in Hamgyeong Province. The source said the rumor was found to be untrue and pulled down the exchange rate.