Voice of America reports that Malaysia has begun to look into a Panamanian vessel suspected of carrying North Korean coal.

Citing local sources and shipping tracking data, VOA said the vessel "Dong Thanh" suspected of carrying coal unloaded from a North Korean ship left Indonesia last Saturday and reached waters near the Malaysian port of Kemaman on Friday.

But the report said the vessel failed to gain approval for port entry.

Malaysian authorities had notified the port about suspicions over North Korean coal and believe an investigation is necessary.

A port notice obtained by VOA reads that "there are clear instructions from the Malaysian government regarding matters involving North Korea."

The document says the vessel in question will be "directed to anchor off port limit upon arrival until the investigation and new instruction given from the authority."

VOA said Malaysia appears to have simply withheld the vessel's entry, but it has in fact begun steps to detain the boat. 

According to a recent report issued by the UN Security Council's North Korea sanctions committee, a vessel named "Wise Honest" was detained by Indonesian authorities in April last year for carrying over 26-thousand tons of North Korean coal.

VOA said this vessel was taken to an area near the Indonesian city of Balikpapan last month where the coal was unloaded and then transferred to a Panamanian-flagged vessel operated by a Vietnamese shipping firm.