South Korean authorities have seized a second ship suspected of supplying oil to North Korea in violation of international sanctions, officials say.
The Panama-flagged tanker, which is named Koti, is being held at a port near the western city of Pyeongtaek.
South Korea has already impounded a Hong Kong-registered ship it suspects of secretly transferring 600 tonnes of refined oil to a North Korean vessel.
The UN imposed sanctions on the North in response to its weapons programme.
The latest vessel seized, which has a mostly Chinese and Burmese crew, is a 5,100-tonne oil carrier, South Korean news agency Yonhap reported.
South Korea revealed on Friday that it was holding the Hong Kong-registered Lighthouse Winmore.