An oil spill from a leaking well off the Brazilian coast "is not over," the National Oil Agency warned Sunday.
"The leaking still has not stopped at some points," the monitoring agency said, referring to images taken Saturday, and data from the Navy that "monitored [1,312 feet] of cracking" early Sunday, the G1 news service reported.
The oil "continues to drift away from the coast," the report added.
On Saturday, Chevron Brazil President George Buck told local media that "the pressure of the deposits was underestimated."
Based on an incorrect calculation, the company used a type of material that lacked sufficient weight needed to contain oil, which then leaked and reached the surface, Folha de Sao Paulo newspaper explained.
Buck on Nov. 13 had insisted that the leak was fully contained, but noted that the incident was still being investigated.
On Friday, the oil agency said that the oil slick was down from 63 square miles on Tuesday to about 11 miles long and 4.5 square miles wide.
The well, which Chevron said began leaking on Nov. 8, is near the Frade field located some 230 miles northeast of Rio de Janeiro, in an area that is a migratory route for whales and dolphins.
According to Chevron, the slick reached a volume of 882 barrels of oil at its worst, on Monday, and dropped to 18 barrels on Friday.
The U.S. oil giant said no oil leaked from the wellhead, and that it is controlling and monitoring the "sheen."
It estimated that between 200 and 330 barrels of oil have seeped into the sea since Nov. 8. The Energy Ministry, for its part, said 220 to 230 barrels of oil are seeping into the ocean daily.
Those estimates have been contested by Greenpeace, which said satellite pictures showed a spill "10 times bigger," and likely reached closer to 3,700 barrels a day.
Copyright Agence France-Presse, 2011