Armed gunmen have hijacked a cargo ship carrying 23 crew off the coast of Somalia, the latest attack near the lawless African country, South Korea's Foreign Ministry said Sunday.

The 20,000-ton-class ship, owned by a Japanese shipping company and registered in Panama, was seized by gunmen Saturday evening in waters 96 miles east of Somalia's port city of Aden, the ministry said in a statement.

The ship Chemstar Venus includes five South Koreans and 18 Filipinos and was carrying unidentified chemicals, the statement said.

The condition and safety of the crew were not immediately known. South Korean officials said they have no information on whether the gunmen were asking for ransom for the sailors' release.

South Korea's Foreign Ministry said it will cooperate with the Japanese government and shipping company to win the early release of the sailors. The name of the Japanese firm was not immediately available.

Somalia, which has had no functioning government since 1991, is the world's top piracy hotspot. It is located along the Gulf of Aden, which connects the Red Sea and the Indian Ocean and is one of the world's busiest waterways with some 20,000 ships passing through it each year.

Somali pirates are trained fighters, often dressed in military fatigues, using speed boats equipped with satellite phones and GPS equipment. They are typically armed with automatic weapons, anti-tank rockets launchers and various types of grenades.

In October, 22 sailors — eight South Koreans and 14 citizens of Myanmar — were released following a month of captivity after their South Korean shipping company paid a ransom to Somali pirates.

South Korea has said it is considering dispatching navy vessels to join several other countries' warships in patrolling the waters off Somalia.

A NATO flotilla of seven vessels is patrolling the Gulf of Aden to help the U.S. 5th Fleet in anti-piracy patrols and to escort cargo vessels. The 5th Fleet said it has repelled about two dozen pirate attacks since Aug 22.

Nevertheless, pirate attacks have surged in the past week, with at least five successful hijackings since Nov. 7, according news reports and figures from the International Maritime Bureau's piracy reporting center in Malaysia.