Updated

The U.S. Navy was tracking a hijacked Japanese tanker off the coast of Somalia on Thursday with the aim of removing the attackers from the ship.

The Navy came to the vessel's aid this week when a warship destroyed pirate skiffs tied to the Japanese boat.

Naval personnel also boarded a North Korean vessel to treat crew members and pirates wounded during an uprising that returned the ship to its rightful control. One hijacker was killed, and the others remain detained on board, including three with gunshot wounds.

The U.S. military said it continued to monitor the two boats Thursday off the southern Somali coast.

"The goal is to get the pirates off the ships so the ships can return to legitimate shipping traffic and transit," said Cmdr. Lydia Robertson, a spokeswoman for the U.S. Fifth Fleet in Bahrain.

She gave no more details, citing operational security.

Two other ships are known to still be held after being hijacked in Somali waters, and officials say negotiations continue with pirates who seized the pair of South Korean-owned vessels and their 24 crew members in May.

A release could come soon, said Andrew Mwangura, Kenya-based program coordinator of the Seafarers Assistance Program, an independent body monitoring pirate attacks. He gave no specific timeframe.

When the Navy boarded the North Korean ship Tuesday at its invitation with a small team of medics, security personnel and an interpreter, the 22-person Korean crew already had regained control of the ship and detained all pirates, the Navy said.

The Navy medics treated three North Korean sailors and three pirates for gunshot wounds. The Korean sailors were taken aboard the American destroyer and treated there for two hours before being returned to their ship.

Shipping officials said the hijacked Japanese-flagged ship, Golden Nori, was carrying a load of benzene when the guided missile destroyer USS Porter fired on and destroyed two pirate boats tied to the chemical tanker on Sunday. Benzene, an industrial solvent, is both highly flammable and can be fatal if too much is inhaled.

The military said it was aware of what was onboard when it fired at the skiffs, sinking both.

The company said it had been told that the tanker's 23 crew — two South Koreans, 12 from Myanmar and nine Filipinos including the ship's captain — had not been injured as of Wednesday.

Somali pirates are trained fighters, in some cases linked to powerful Somali clans, outfitted with sophisticated arms and equipment, including GPS satellite instruments. They have seized merchant ships, ships carrying aid, and once even a cruise ship.

U.S. Navy officials have said pirates may be getting their small open boats towed to the shipping lanes by vessels they pay off or commandeer. It's doubtful, they said, that these open skiffs could cover hundreds of miles of open ocean on their own.

(Copyright 2007 by The Associated Press. All Rights Reserved.)