A South Korean fishing boat with 43 sailors aboard has been hijacked by pirates off the coast of Kenya, South Korea's foreign ministry says.
The ministry said the crab fishing vessel was seized off Lamu Island on 9 October.
South Korean media reported the boat had been taken to a pirate stronghold in northern Somalia.
Kidnapping for ransom is common in Somalia, which has had no effective government for two decades.
In a statement, South Korea's foreign ministry said it was investigating the incident and had set up an emergency team at its embassy in Kenya.
The statement did not say if contact with the pirates had been made or if a ransom had been demanded.
South Korea has a warship on anti-piracy patrol in the waters of the Indian Ocean and Gulf of Aden off Somalia.
The area is one of the world's busiest shipping lanes, leading to the Suez Canal.
European naval officers fighting piracy in the waters warned earlier in October that pirates would likely be more desperate with the onset of the piracy season as their success rate was declining.
The European Union's naval force, Navfor, estimates that the pirates' success ratio - the number of successful hijackings versus the number attempted - has dropped from 50% a few years ago to 20-30% this year because of international patrols.
The patrols have forced the pirates to range a wider area of the Indian Ocean in search of targets.
But Navfor also warned that hostages are being held for a longer period on average and that ransoms being demanded - and paid - are breaking new records.