Somali pirates on Monday (November 5) freed a Taiwanese vessel held since May, following the release a day earlier of two South Korean ships that were then sailed to Yemen under U.S. Navy escort. Officials said the Taiwanese ship and its 12 crew, eight Kenyan and four Taiwanese, were freed from a pirate-held port north of Mogadishu. The United States Navy's Fifth Fleet, based in Bahrain, confirmed the release, and said it was providing unspecified assistance to the ship. The Taiwanese vessel was liberated as five U.S. warships were escorting two South Korean vessels to Yemen, after their release on Sunday (November 4) following five months in captivity. The two South Korean boats are registered in Tanzania's Zanzibar islands. The waters off Somalia are some of the most dangerous shipping lanes in the world. A statement by the South Korean Foreign Ministry said all 24 crew -- 10 Chinese, four South Koreans, four Indonesians, three Indians and three Vietnamese -- were safe. Gunmen attacked the vessels, the Mavuno 1 and Mavuno 2, off the Somali coast on May 15 as they were travelling to Yemen. Somali pirates are still holding two other craft: a Japanese-owned, Panama-flagged Golden Nori chemical tanker they seized last week and the Al Marjan cargo ship registered in Comoros. The U.S. Navy said it was monitoring those ships. Dai Hong Dan, a North Korean ship which was seized by pirates off Somalia's coast last week, was seen at the southern Yemeni port of Aden on Tuesday (November 6) days after the cargo ship's crew managed to regain control of the vessel with assistance from the U.S. navy. Piracy has been rife off Somalia since the country slid into chaos after warlords toppled military dictator Mohamed Siad Barre in 1991. Many pirates claim to be "coastguards" protecting their waters against illegal fishing and dumping of toxic waste.