The United Nations Security Council is expected to adopt a much-delayed resolution aimed at penalizing North Korea for its latest nuclear test next week as the US and China have narrowed their differences on proposed curbs on its coal exports, diplomatic sources said Wednesday.

"The US and China seem to have narrowed their gap pretty much on an effective and verifiable frame through which they will be able to regulate the North's coal exports," a source close to the matter told Yonhap News Agency on condition of anonymity.

Other sources expected that consultation with the other permanent members of the UNSC including Russia will start soon and that the final version of the resolution will likely be adopted no later than the Thanksgiving holiday that falls in the middle of next week.

In September, the North conducted its fifth and the strongest-ever nuclear test, drawing strong condemnation from the international community.

The UNSC immediately launched the process of drawing up a resolution, but it has been delayed reportedly due in part to a failure by Washington and Beijing to iron out their differences.

The focus has been placed on how to cover the "loopholes" in the previous resolution adopted in March after the North's fourth nuclear test in the same month, which allowed trade related to the livelihood of the North Korean people.

The North is suspected of taking advantage of it in acquiring hard currency necessary to continue its missile and nuclear programs.

The US has pushed to remove the "exception" but failed to enlist support from China, the closest ally to Pyongyang. The North's coal exports account for the largest portion of its trade with China.  (Yonhap)