Chinese exports of fuel to North Korea surged more than sixfold on-year in September, the Tokyo Shimbun reported on Thursday citing customs statistics. The North imported 22,800 tons of aviation fuel, gasoline and diesel.

The daily quoted a source in the North as saying that the North seems to have used most of it at an air show in Wonsan on Sept. 24-25, which featured MiG-29 and Su-25 fighter jets.

Back in March, the UN Security Council in principle banned countries from exporting aviation fuel to the North but made exceptions for fuel for civilian jets and humanitarian purposes.

But there is clearly a loophole. "It's difficult to check whether the North is importing jet fuel for fighter jets and just claiming to use it for civilian aircraft," a source said.

In fresh sanctions imposed last month in response to the North's latest nuclear test, the UNSC again failed to ban the sale of jet fuel to Pyongyang completely.

