China-bound exports of North Korea's natural resources should be blocked to improve the efficiency of economic sanctions being ramped up against the reclusive communist country in the wake of its recent provocative actions, a local think tank said Monday.

Pyongyang's total exports have been shrinking in recent years, mostly affected by a marked drop in overseas sales of its natural resources. The Korea Economic Research Institute cited the correlation as a major avenue that the international community should tap into to improve efficiency of sanctions on the country.

"The recent shrinkage in exports was the result of a significant drop in exports of its natural resources ... Its natural resources exports continued to decline into the third quarter of last year," the think tank said in a report.

"Behind the positive growth of the North Korean economy after 2010 was its abundant resources buried under the ground and high-quality labor force, which combined to expand its trade with China," it added. "Pyongyang's efforts to secure foreign currencies could hit a snag should the China-bound exports continue to decline."

The report said that North Korea's natural resources exports to China rose to an all-time high of $1.84 billion in 2013 but fell to $1.52 billion in 2014. During the same period, the ratio of natural resources to its total overseas shipments fell from 63.2 percent to 53.7 percent. 

North Korea depends almost entirely on China for its overseas trade. The heavy reliance on China could further increase down the road after South Korea recently shut down the operation of an inter-Korean industrial complex in the North's border city of Kaesong in apparent retaliation against its recent series of provocative acts. 

The North drew international condemnation by conducting its fourth nuclear test early this year, which was followed by a recent rocket launch which is regarded by many experts as a disguise for a test of its long-range missile technology. (Yonhap)