The Greek operator of the Panamanian-registered oil tanker Devon confirmed that the ship had leaked oil off the southern Taiwanese port of Kaohsiung, but said only a small amount was spilled.
Earlier port officials had said a one km long spill had been left in the Taiwan Strait after the ship was found to be leaking oil when it approached a dock.
"The spillage was minimal - no more than two barrels at most," a spokesman for Piraeus-based ship operator European Navigation Inc. said.
The 269,895 dwt vessel was anchored in port, and an investigation was being held into where the leak had originated, he said. An improperly closed valve was suspected as a possible source.
The 1975-built vessel had loaded a cargo of 1.9 million barrels of crude for Taiwan's China Petroleum Company (CPC) at the Iraqi port of Mina al Bakr in early November, the spokesman said.
Kaohsiung port officials earlier said workers had managed to stop the spill, but not before the oil had formed a 100-by-1,000 m spill.
The spill had been contained by specialized booms, and recovery efforts were under way.
No crude had been offloaded, a China Petroleum spokesman said. Cleanup of the spill is the responsibility of the shipper
, he added.