A Spanish government official says the oil tanker Prestige hasn't leaked any oil since it sank.
Environmentalists have been hoping the tanker's remaining cargo would turn solid in the cold sea and stay inside the vessel.
Fernandez de Mesa said he had met with more than 20 experts who all agreed the estimated 70,000 tons of oil had solidified.
"There have been no new oil spills since the boat went down on Tuesday," said Arsenio Fernandez de Mesa, the government's chief representative in the northwestern region of Galicia.
"We're controlling the evolution of the slicks both where the tanker sank as well as the around the coast of Galicia," he said. "There have been no new ones beyond that caused by the actual sinking Tuesday."
In Madrid, the Development Ministry said it had started legal action to seek compensation for damages caused by the tanker. He said authorities were not yet able to estimate the size of the slick left in the immediate zone where the tanker sank.
"What we do know is that the evolution of the slick is northward and that's a good thing as it stays clear of the coast," Fernandez de Mesa said.
He added, however, that heavy winds forecast for the next few days could blow the slick in a different direction.