A Russian-owned tanker has been held in South Korea in a probe into alleged illegal transfers of oil to North Korea.
The vessel was named as the 2,000-dwt Katrin (built 1987), flagged in Panama, according to the Yonhap news agency.
It is docked in Busan.
The ship's owner, a Russian national, is denying the allegations.
It was inspected twice in joint operations undertaken by South Korea's spy agency and customs office in February when it entered Busan for maintenance.
South Korea has detained eight ships on suspicion of violating UN sanctions.
