The MV Faina is carrying a shipment of battle tanks
Somali pirates holding a Ukrainian ship with a cargo of military tanks off the Somali coast have threatened to blow it up if they are not paid a ransom.
A pirate spokesman told news agencies by satellite telephone that the ransom of $20m (£12m) must be paid by Monday night or the ship would be destroyed.
He said the pirates were ready to die along with the crew.
US warships have surrounded the MV Faina and a Russian frigate is on its way to help in the operation.
The Kenya-bound ship, together with its mainly Ukrainian crew of 21 and cargo of 33 tanks, was seized on 25 September.
One member of the crew, believed to be Russian, died of a stroke shortly afterwards.
"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 from aboard the vessel.
"After three days, starting from tomorrow, the news of the ship will be closed. Either we achieve our goal and get the ransom or perish along with the ship, its crew and cargo."
The pirate spokesman repeated the ultimatum in a conversation with the Spanish news agency Efe.
Piracy is rife in the busy shipping lanes near to Somalia's coast and along the Gulf of Aden, where dozens of boats have been hijacked this year.
Somalia has lacked a functioning central government since 1991 and has been afflicted by continual civil strife.