DUBAI - Pirates have seized a Saudi-owned supertanker fully laden with oil off east Africa, capturing the biggest vessel yet in a shipping zone where Somali pirates strike almost daily, the U.S. navy said.

Saudi-owned television station Al Arabyia said the Sirius Star had been freed, citing an unnamed official Saudi source, but as Daily News went to press, the U.S. navy and Saudi Aramco, which owns the supertanker, both said they had no knowledge of any release.

"This is unprecedented. It's the largest ship that we've seen pirated," said Lieutenant Nathan Christensen, a spokesman for the U.S. Fifth Fleet. "It's three times the size of an aircraft carrier." The ship held a cargo of as much as two million barrels of oil -- more than one quarter of daily production.