The U.S. Navy says more American warships have been sent to the east coast of Somalia, where a vessel carrying more than 30 tanks and other military equipment is being held by pirates. As VOA Correspondent Alisha Ryu reports from our East Africa Bureau in Nairobi, there are conflicting reports about the final destination of the cargo.

The U.S. Navy's Fifth Fleet in Bahrain declined to say how many of its warships are stationed off the coast of central Somalia. But spokeswoman Lieutenant Stephanie Murdock says several have joined the Navy destroyer USS Howard, which was deployed to the area earlier to keep an eye on the hijacked MV Faina and its sensitive cargo.  

"There are several Fifth Fleet ships currently in the vicinity of Motor Vessel Faina," she said. "In addition to visual watch, they have got basic bridge-to-bridge communication with the ship, so they are monitoring the situation."

About 60 Somali pirates operating from the central Somali town of Haradhere seized the Ukrainian-operated ship Thursday as it sailed toward the Kenyan port of Mombasa.  

The pirates are holding 20 Russian, Ukrainian, and Moldovan crew members, 33 Russian-built T-72 tanks, and a substantial number of rocket-propelled grenade launchers, anti-aircraft guns and ammunition. They have demanded a $20 million ransom for their release. The ship is believed to be anchored about 11 kilometers off Somalia's eastern coast.

With permission from the pirates, one of the Russian hostages spoke to VOA by satellite telephone. Identifying himself as First Mate Viktor Nikolsky, he confirmed reports from Moscow that the ship's Russian captain Vladimir Kolobkov has died of natural causes.

"He died due to high blood pressure," he said. "Now, I am the captain."

A Russian frigate is also heading to Somalia, amid worries that the hardware could end up in the hands of an ambitious factional leader or militant al-Qaida-linked Islamists, who have been waging a bloody insurgency against Somalia's Ethiopia-backed government since 2007.

The spokesman for the Haradhere-based pirates Sugule Ali tells VOA that his group has no intention of keeping or selling any of the ship's cargo. Ali says they are only interested in securing the ransom. He says there can only be two ways to resolve the stand-off - pay the ransom or watch everyone on board die.

The Kenyan government says it purchased the tanks and arms for its military and insists the ship's final destination was Mombasa. But the head of the Mombasa-based Seafarers' Assistance Program Andrew Mwangura says there is evidence to suggest that the consignment was destined for southern Sudan.

"According to our records, since October last year, there were four ships with the same cargo, the same material and the destination of the cargo was southern Sudan," he said.

The government of South Sudan vehemently denies it has purchased or received any military hardware during the past year.

Southern Sudanese rebels fought a two-decade-long civil war with the government in Khartoum before signing a peace agreement in 2005. But the accord has not been fully implemented and tension has been rising between the rivals in recent months.