Chinese customs authorities say the country purchased 11.5 million dollars' worth of iron ore from North Korea in June. That's down 1.7 percent from the same month last year.

But, imports in each month from January through May recorded year-on-year increases.

Imports in the first half reached 86 million dollars, 2.4 times the amount in the same period the previous year.

Purchases of iron ore from North Korea are banned in principle by a UN Security Council sanctions resolution, but are permitted if the transactions exclusively serve livelihood purposes.

In February, China announced it would stop buying coal from the North for this year in line with another UN Security Council resolution.

Coal exports have been North Korea's main source of foreign currency.

China's total iron ore imports from the North last year amounted to less than 10 percent of its coal purchases.

NHK's reporter says the North wants to cover the drop in foreign currency earnings generated from coal shipments with exports of iron ore to China.