The Greek tanker with a crew of 19 is carrying refined petroleum from Europe to the Middle East. It was ambushed Friday in the Gulf of Aden, said Noel Choong, who heads the International Maritime Bureau's piracy reporting center based in Malaysia. He said pirates chased and fired at the ship before boarding it.
In Somalia, a man claiming to be spokesman of the pirates holding the Ukrainian ship said the hijackers want $35 million to release the vessel. But there was no way to immediately verify his claim that he represented the pirates.
On Thursday, pirates seized the Ukrainian-flagged ship Faina en route to Kenya with 33 Russian-built T-72 tanks and a substantial quantity of ammunition and spare parts. Russia's navy said Friday it had dispatched a warship to the area, and the United States said American naval ships were tracking it with special concern because of the weaponry on board.
The hijackings were the latest in a series of audacious maritime attacks off the coast of Somalia, a war-torn country that has been without a functioning government since 1991.
A U.S. defense official said the destrost any military action to liberate it.
"Any one who tries it will be responsible for the consequences," Abdulkadir said.
A Russian Web site posted what it said was an audio recording of a telephone conversation with the Ukrainian ship's first mate. He said the hijackers are seeking a ransom and have anchored close to the Somali shore.
There was no way to immediately confirm the authenticity of the report on Web site Life.ru. Calls to the phone number listed on the site went to an answering machine at the publisher of two established tabloids that have reportedly reliably on news in the past - one of them also called Life.
On the recording, a man who identified himself as first mate Viktor Nikolsky said the hijackers were asking for a ransom but he did not know how much. Life.ru showed images of what it said were the Russian passports for both Nikolsky and the ship's captain, Vladimir Kolobkov.
Nikolsky said there were 35 people on the ship - 21 of them crew - and most were being held in a single overheated room, he added.
Nobody aboard the Faina was injured, but the captain was suffering from heatstroke and his condition was "not so good," the man identified as Nikolsky said. It was unclear exactly when the purported conversation took place.
Ukrainian officials had said there were 21 crew members aboard - 17 Ukrainians, three Russians and a Latvian.
Nikolsky said the ship was anchored near the Somali town of Hobyo and that two other apparently hijacked ships were nearby.
Hobyo is in the central region of Mudug, south of Puntland. It is a natural port and does not have any facilities.
Kenyan Defense Department spokesman Bogita Ongeri said the Ukrainian vessel was seized in international waters in the Gulf of Aden. He said that the pirates hijacked the ship beyond 200 nautical miles away from the coast of Puntland. Two hundred nautical miles in maritime law mark the end of a country's territorial waters.
Long a hazard for maritime shippers - particularly in the Indian Ocean and its peripheries - high-seas piracy has triggered greater alarm since the Sept. 11 terrorist attacks on the United States because of its potential as a funding and supply source for global terrorism.
Pirate attacks worldwide have surged this year and Africa remains the world's top piracy hotspot, with 24 reported attacks in Somalia and 18 in Nigeria this year, according to the International Maritime Bureau's piracy reporting center.
French President Nicolas Sarkozy this month called on other nations to move boldly against pirates, calling the phenomenon "a genuine industry of crime."
