South Korea has sent a warship to intercept an oil tanker it believes was hijacked by Somali pirates.
South Korea's foreign ministry says the supertanker Samho Dream was apparently seized in the Indian Ocean on Sunday with 24 crewmembers on board.
There has been no confirmation the ship was hijacked, but ministry officials say they reached that conclusion based on the ship's last communications.
The tanker was headed to the United States carrying oil worth up to $170 million.
The South Korean warship, the Yi Sun-shin, was already patrolling the waters near Somalia as part of international anti-piracy activities.
The Seoul government says it will put top priority on the lives and safety of the tanker's crewmembers, but will not directly negotiate with the pirates.
The ship's crew includes 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.
Pirates usually release the hijacked ships and their crews unharmed after receiving a ransom, sometimes worth millions of dollars.
Somali pirates have hijacked two large oil tankers in the past. The Saudi-owned Sirius Star was hijacked in 2008 and released after a $3 million ransom was paid.
Last year, pirates seized a Greek-owned tanker, the Maran Centaurus. That ship was freed for a ransom of at least $5.5 million.
Some information for this report was provided by AP, AFP and Reuters.