A stateless 3,000-ton ship, allegedly seized for violating U.N. sanctions, is seen near Gamcheon Port in Busan, April 3. Yonhap

South Korea has seized a stateless vessel that allegedly engaged in activities in violation of U.N. sanctions in waters off the country's south coast, security sources said Wednesday.

The 3,000-ton cargo ship DEYI, reportedly en route to Russia from North Korea via China, was captured in waters off Yeosu around Saturday, they added.

Thirteen were aboard the ship, including a Chinese captain and other Chinese and Indonesian crewmembers.

South Korea's Coast Guard is said to have moved the ship and docked it in waters off the southeastern port of Busan after the crewmembers refused orders to stop the vessel.

"Our government is conducting an investigation, in close coordination with the United States, into the concerned vessel's alleged violation of the U.N. Security Council resolutions on North Korea," an official at the foreign ministry said.

The official did not provide further details.

It was not immediately known whether the ship was involved in any sanctions-violating activities. Authorities were reportedly unable to confirm what the vessel is carrying as the crew is refusing to open the cargo hold.

U.N. Resolution 2397, adopted in 2017, allows a country to seize, inspect and impound any vessel within its territorial waters that is suspected of engaging in prohibited activities with North Korea. (Yonhap)