Sao Paulo, Brazil (CNN) -- Brazil's Federal Police agency said Thursday it's investigating an oil spill at a site off the coast of Rio de Janeiro being explored by the U.S. oil company Chevron.
The Federal Police's Rio de Janeiro office said in a statement those responsible for the "environmental accident in the Campos Basin" could face sentences of up to five years in jail if found guilty.
Brazil's Oil and Gas Regulator (ANP) said Chevron reported a seepage in its offshore Frade project November 8 and said that between 200 and 330 barrels of oil per day leaked into the ocean. The resulting slick was about 163 square kilometers (100 square miles), Chevron said, and was situated about 120 km (75 miles) off the coast of the state of Rio de Janeiro.
Chevron moved to cap an assessment well Wednesday that it says is the source of the seepage, ANP said.
Chevron told ANP that 18 vessels were on the scene to take care of the clean-up. But according to the Folha de Sao Paulo newspaper, Federal Police did a fly-over of the site Tuesday and saw only one vessel.
"The reports do not correspond with the reality of the facts," Fabio Scliar, from the police environment department, told Folha de Sao Paulo. "I want to understand what happened."
ANP said the spill is dispersing and moving away from the Brazilian coast, so it does not appear to threaten Rio's world-famous beaches. But it does raise questions about how prepared Brazil is for the development of its offshore "pre-salt" deposits, which are expected to turn the country into a major oil exporter in the coming years.