(Adds details, quotes, changes dateline, previous NAIROBI)

By Abdiqani Hassan

BOSASSO, Somalia, Dec 12 (Reuters) - Somali pirates who seized a Japanese chemical tanker in October and were demanding a ransom have left the vessel without hurting any of its crew, the U.S. military and local officials said on Wednesday.

The Panama-registered Golden Nori was carrying benzene from Singapore to Israel when it was hijacked on Oct. 28, just off Somalia in one of the world's most dangerous shipping lanes.

Saeed Mohamed Rage, fishing and marine minister for Somalia's northern Puntland region, said the hijackers and the owners of the tanker had struck a deal on Tuesday.

"Then late last night the pirates were able to disembark the vessel heading towards the west of Bosasso town," Rage told Reuters. "Now they are at large."

Reached by satellite phone at an undisclosed location, one pirate said they were paid a half-a-million dollar ransom.

"We've been paid $500,000," said the man, who gave his name as Abdi Habo. "But I don't want to discuss this matter further."

Earlier this month, U.S. Navy ships cornered the Golden Nori off the Puntland coast, opening fire and sinking speedboats used by the pirates that the captured tanker was towing behind it.

"All the pirates are off the vessel. The U.S. Navy has a ship nearby. We're standing by to offer assistance," said Lieutenant John Gay of the U.S. Navy Central Command in Bahrain.

"All the crew is safe." He gave no further details on how the pirates left the ship. The tanker's 21 sailors are believed to be from Myanmar, the Philippines and South Korea.

The U.S. Navy, which has had a long presence in the region, has concentrated its anti-piracy efforts along Somalia's coast after several ships were hijacked there this year.

Gay said the Golden Nori was on its way to another port.

He also said it was the first time since late 2006 that the Somali coast was free of ships seized by pirates.

The attackers had been expected to demand a ransom of at least $1 million for the safe release of the tanker. Ransom demands are normally determined by the size of the ship, its cargo and the nationalities of its crew, experts say.

In August, Danish media said Somali pirates freed a Danish cargo ship, the MV Danica White, and its five Danish sailors after a security company paid a $1.5 million ransom.

Piracy has been rife off Somalia since warlords toppled military dictator Mohamed Siad Barre in 1991. (Writing by Daniel Wallis; editing by Elizabeth Piper)

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