The head of the Brazilian Federal Police's environmental crimes unit has questioned the legality and methods being used by U.S.-based Chevron Corp. to clean up an oil spill along the Atlantic coast.

Fabio Scilar told Brazilian media Saturday that the San Ramon, California-based company was "pushing" the oil to the bottom of the sea with high-pressure streams of sand, committing an environmental crime by polluting the ocean and endangering coral reefs.

The Federal Police has informally asked the oil company to change its clean-up strategy, Scilar said.

The spill occurred two weeks ago at a Chevron-operated appraisal well in the vicinity of the supermajor's offshore Frade field, located 370 kilometers (230 miles) off the coast of Rio de Janeiro state at a depth of approximately 1,200 meters (3,930 feet) in the Campos basin, Brazil's main oil-producing area.

Between 200 barrels per day (bpd) and 330 bpd of crude spilled into the ocean from Nov. 8 to Nov. 15, but the flow has slowed in the past few days because the company capped the well, the National Petroleum Agency, or ANP, said.

The oil sheen has dissipated and was about 18 kilometers (11 miles) long on Friday, the ANP said.

Some Brazilian officials have disputed the figures, claiming that the spill is much larger.

The head of Chevron's Brazilian unit, George Buck, said Friday that the company underestimated the pressure in one of the wells, possibly leading to the spill.

"There has never been any oil flow from the wellhead and current monitoring indicates oil from nearby seep lines on the ocean floor has been reduced to infrequent droplets," Chevron said Thursday.

Chevron, which has a 51.7 percent stake, is the lead operator in the Frade field.

Brazilian state oil giant Petrobras has a 30 percent interest in the project and the Frade Japao Petroleo Ltda. consortium controls the remaining stake.