Somali pirates who seized a Ukrainian ship with a cargo of battle tanks said they`ll sink it if the $20 million ransom they`ve demanded isn`t paid by tomorrow, Bloomberg reported.

``Either we receive our money by tomorrow, or never,`` Sugule Ali, a spokesman for the pirates, said by satellite phone, in comments posted on the Web Site of Russian state broadcaster Vesti-24. He ``gave it to be understood`` that the ship, the Faina, could be sunk tonight or tomorrow, Vesti said.

Somali pirates seized the Faina, a Belize-flagged vessel with a crew of 17 Ukrainians, three Russians and one Latvian, on Sept. 25, the Ukrainian Foreign Ministry said. It was carrying at least 30 Soviet-designed T-72 tanks to Kenya.

It`s surrounded by six U.S. warships, Vesti said. A Russian warship, the Neustrashimy or Intrepid, is on its way to the coast of Somalia and is now on exercises in the Mediterranean.

Russian television today showed footage of sailors involved in the naval exercises sightseeing at Roman ruins near Tripoli in Libya. It`s not clear when the Neustrashimy is expected to reach Somalia.

Sugule Ali said negotiations with the owners of the Faina are still under way.

One of the Russians on the Faina, the captain, Vladimir Kolobkov, died of a heart attack on Sept. 28, Vesti said.