FACTBOX: Ships held by Somali pirates

(Reuters) - Pirates seized a Greek-owned cargo ship off the coast of Somalia on Sunday, Greece's Merchant Marine Ministry said.

Below are some of the ships believed to be still held as well as some details on the increase in piracy:

STOLT STRENGTH: Seized November 10. The chemical tanker had 23 Filipino crew aboard. It was carrying 23,818 tonnes of oil products.

CHEMSTAR VENUS: Seized November 15. The tanker was traveling from Dumai, Indonesia, to Ukraine. It had 18 Filipino and five South Korean crew.

NAMES UKNOWN: Seized on December 10. Pirates hijacked two Yemeni fishing vessels with a total of 22 crew in coastal waters in the Gulf of Aden. Five crew reportedly escaped.

NAME UNKNOWN: Seized on December 16. A yacht with two on board, an Indonesian tugboat used by French oil company Total. Pirates also hijacked the Chinese fishing vessel Zhenhua-4 with 30 Chinese crew aboard but it was freed the next day.

BLUE STAR: Seized on January 1, 2009. The Egyptian merchant ship was sailing east with a cargo of 6,000 tonnes of urea, a product used as a fertilizer. It had 28 Egyptian crew aboard.

LONGCHAMP: Seized on January 29, 2009. The liquefied petroleum gas tanker, built in 1990, has 13 crew on board, 12 Filipinos and one Indonesian. The tanker has a capacity of 3,415 tonnes.

SALDANHA: Seized on February 22, 2009. The Maltese-flagged cargo ship, sailing to Slovenia, has 22 crew and was loaded with coal.

PIRACY INCREASES:

-- In 2008 there was a worldwide total of 293 incidents of piracy against ships - more than an 11 percent increase on the year before.

-- The increase is attributed to the number of attacks in the Gulf of Aden with 111 incidents reported on the east coast of Somalia and the Gulf of Aden. This is an increase of nearly 200 percent from 2007.

-- All types of vessels with varying freeboards and speeds were targeted. The pirates boarding the vessels were also better armed than in previous years and prepared to assault and injure the crew.

Sources: Reuters/International Maritime Bureau Piracy Reporting Center/Lloyds List/Inquirer.net