A Mongolian-flagged freighter carrying 16 North Korean crew is

believed to have sunk early this morning off the southwest coast of Korea, Yeosu and Jeju maritime

authorities report.

All contact ceased with the 4000 ton freighter after it issued a distress signal at 1.19am , 63 kilometers southeast of Geomun Island.

It is believed the vessel was transporting a shipment of

steel from Chongjin to a port in China.

Three of the original 16 crew members rescued by the maritime authorities have been transferred to a hospital on Jeju Island to undergo treatment.

Investigations are continuing.