The Japan Coast Guard was cited as saying that four of the 11 people aboard the tanker had been rescued, but their conditions remained unknown. The Japanese rescue services are continuing operations with aircraft and a patrol vessel, the broadcaster reported.
The local coast guard station received a distress signal at around 7:00 a.m. (22:00 GMT Tuesday) from the Keoyoungsun chemical tanker that was reportedly tilting west of Mutsurejima Island, the report said.
The tanker carried two South Koreans, eight Indonesians and a Chinese on board, the report also said.
No data on whether any cargo was on board the vessel or if the incident caused a chemical spill have been provided, the report added.