* Somali pirates seize huge crude oil supertanker
* Ship en route from Iraq to US, chartered by Valero
* Last big tanker held 2 months, freed for ransom (Updates with Valero comments, details)
SEOUL, April 4 (Reuters) - Somali pirates seized a supertanker carrying as much as $170 million worth of crude oil from Iraq to the United States on Sunday, officials said, the latest sign that sea gangs may be targeting bigger quarry.
The 333-meter-long (1,092-foot) Samho Dream, which can carry more than 2 million barrels of crude oil, was hijacked and its crew of five South Koreans and 19 Filipinos was taken hostage, South Korea’s foreign ministry said in a statement.
U.S. refiner Valero Energy Corp (VLO.N) said it was the owner of the crude oil cargo aboard the Samho Dream, which was hijacked off the east African coast. The cargo was bound for the U.S. Gulf Coast, Valero spokesman Bill Day said.
Increasingly brazen pirate activity has driven up insurance costs, forced some ships to go around South Africa instead of through the Suez Canal, and secured millions of dollars in ransoms.
A Nairobi-based maritime group said the tanker had been seized by Somali pirates, and a pirate source named Mohamed said the ship was now heading for Haradheere, the port and pirates’ base at which many ships are held during ransom negotiations.
While attacks in the Gulf of Aden and the Indian Ocean have become an increasing risk for all vessels in recent years, it is rare for pirates to successfully seize the kind of massive supertankers that carry most Gulf crude to refiners.
The first successful assault on a very large crude carrier (VLCC) occurred in late 2008 when pirates took the Saudi-owned Sirius Star, the biggest ship hijacking to that date.
Another, the Greek-flagged Maran Centaurus, was seized last November and held for nearly two months until a ransom believed to be between $5.5 million and $7 million was paid.
"I can confirm that the cargo was chartered by Valero," Day said. "It was bound for the Gulf Coast. We are aware of the situation and we’re monitoring it along with the ship’s owner."
Valero is based in San Antonio.
The 319,000 deadweight tonnage Samho Dream, which was built in 2002, is carrying crude oil that could be worth as much as $170 million at current oil prices. It holds the equivalent of more than one day’s worth of Iraqi exports. (Reporting by Kim Yeon-hee and Jon Herskovitz, additional reporting by Erwin Seba in Houston; editing by Tim Pearce, Jonathan Leff and Will Dunham)