The pirates who hijacked an arms-laden Ukrainian tanker off the coast of Somalia threatened Friday to destroy the ship if no ransom is paid, a spokesman for the bandits said.

The MV Faina is surrounded by U.S. warships, and a Russian frigate is heading toward the scene, raising the stakes for a possible commando-style raid on the ship.

"We held a consultative meeting for more than three hours today and decided to blow up the ship and its cargo — us included — if the ship owners did not meet our ransom demand," Sugule Ali told the Associated Press when a reporter called the ship via satellite telephone.

"After three days, starting from tomorrow, the news of the ship will be closed. We know what to do next," he said.

The pirates had said Thursday they were willing to negotiate their ransom demand of $20 million US, after nearly two weeks of insisting they would never lower the price.

Pirates have seized more than two dozen ships this year off the Horn of Africa, but the hijacking of the MV Faina has drawn the most international concern because of its dangerous cargo: 33 tanks and other heavy weapons.

NATO ministers agreed Thursday that they would have seven ships in the area within two weeks. Six U.S. warships already surround the Faina off the central coast of Somalia, and helicopters buzz overhead daily. Russia announced it would co-operate with the West in the fight, and several European countries have said they would launch an anti-piracy patrol.

Ukrainian Defence Minister Yuriy Yekhanurov has said that Ukraine does not want foreign countries to use power to take the ship. Most of the 20 remaining crew members aboard the Faina are Ukrainian.

"We are against a forceful scenario, we believe there need to be negotiations," he said. "What is most important is people."

20 Philippine seamen freed from another hijacked ship

Officials said earlier Friday that 20 Philippine seamen were freed Thursday from a hijacked ship where they had been held by Somalian pirates for more than 80 days.

Esteban Conejos, Philippine foreign affairs undersecretary, said the all-Philippine crew of the Japanese-operated bulk carrier Stella Maris seized in July was freed late Thursday. He said the sailors were "well and safe" and their ship was headed to Muscat, Oman.

But 47 Filipinos on three other ships are still in the hands of Somalian pirates, he said.

Pirates also released 29 Iranian seamen and their cargo ship hijacked in July, Iran's official IRNA news agency said Friday.

A Somalian official said a ship carrying cement to the East Africa country was hijacked late Thursday.

Ali Abdi Aware, foreign minister of the semiautonomous region of Puntland in Somalia, said the crew of the ship hijacked late Thursday is believed to be Syrian and Somalian.

Somalia has been impoverished by decades of conflict, and piracy by Somalian gangs has emerged as a lucrative racket that brings in millions of dollars in ransoms. The pirates rarely harm their hostages.

Most pirate attacks occur just north of Somalia in the Gulf of Aden, one of the world's busiest shipping lanes. But recently pirates have been targeting the Indian Ocean waters off eastern Somalia.

Somalia, a nation of around eight million people, has not had a functioning government since 1991.