South Korea's foreign ministry says pirates, probably from Somalia, have hijacked an oil tanker.
The ministry says the tanker, the Samho Dream, was on its way from Iraq to the United States when it was seized Sunday off the coast of East Africa.
It says the ship has a crew of five South Koreans and 19 Filipinos.
Somali pirates have been especially active in recent weeks, taking advantage of good weather to hijack 16 ships since the beginning of March.
International naval forces have stopped numerous attacks and detained dozens of pirates. But the forces cannot fully cover the vast areas of the Indian Ocean and Gulf of Aden in which the pirates operate.
Pirates usually release the hijacked ships and their crews unharmed after receiving a ransom, sometimes worth millions of dollars.
Some information for this report was provided by AP, AFP and Reuters.