Italian authorities on Wednesday were trying to determine how serious and extensive the spill was. So far, they said it did not appear alarming.
The ship contains about 500,000 gallons of heavy fuel and other pollutants, and there are fears that the chemicals could endanger dolphins, whales and other marine life.
Authorities hope to pump fuel from the ship, but due to bad weather the effort was suspended again Wednesday.
Floating barriers placed around the ship to protect the water were lifted by winds, allowing the oily film, consisting of a thin sheen of hydrocarbons, to spread throughout the bay.
According to Civil Protection, the agency overseeing the rescue effort, there doesn't appear to be reason for alarm, noting that over a week ago there was also a leak of a small amount of diesel and lubricants that turned out not to be serious.
Seventeen people have died in the Jan. 13 cruise ship disaster. Fifteen others are still listed as missing.
See photos of the cruise ship Costa Concordia off the coast of Italy.
The Associated Press contributed to this story.
