Japan's public broadcaster NHK reports that the Japanese government filed a report with the UN Security Council last year on North Korea's suspected violations of sanctions resolutions.

Citing sources close to the Security Council, NHK said the Japanese government informed the council's sanctions committee last November of two apparent ship-to-ship transfer cases in which North Korea's involvement was suspected.

In conveying the report in writing, Japan said a North Korean-registered tanker was detected alongside a Singaporean-flagged tanker in high seas of the East China Sea from the night of September 12th to the next morning. 

The document said a hose between the two vessels raised the possibility that refined petroleum products were being transferred between the two. 

In another incident, a North Korean tanker subject to UN sanctions and a Singaporean-registered tanker were spotted alongside each other in the same area on October 28th.

The sources close to the Security Council say these cases will be included in a report by the sanctions committee that is due to be released as early as March, and the council will likely convene talks to discuss the possible violation of sanctions resolutions.