US oil company Chevron says it accepts full responsibility for an oil spill off the coast of Brazil.Chevron said it had underestimated the pressure of underwater oil deposits while drilling, causing oil to rush up the bore hole and seep into the surrounding seabed.Brazilian regulators said 416,400 litres had leaked since the accident happened almost two weeks ago.Chevron said the leak had now been plugged.But the head of Chevron\'s Brazil operation, George Buck, said there continued to be a residual oil flow from undersea rock near the well in the Frade oil project, 370km (230 miles) off the Brazilian coast.Earlier this week, Brazil\'s Energy Minister Edison Lobao said the company would be \"severely punished\" if it was found to have failed in its environmental responsibilities.\'Questionable methods.Chevron initially estimated that 400-650 barrels of oil had formed a sheen on the water after seeping from the seabed near the well.But the international environmental group Skytruth said satellite images suggested the spill was many times bigger.Police environment experts have been trying to assess the scale of the spill.Head of the Federal Police Environmental Division Fabio Scliar also questioned the methods Chevron was using to clean up the spill.Mr Scliar said the company was \"pushing\" the oil to the bottom of the sea, rather than gathering it, putting corals in the area at risk of pollution.In recent years Brazil has discovered billions of barrels of oil in deep water that could make it one of the world\'s top five producers.So far there has been little public debate about the environmental dangers of offshore drilling.Political discussion has instead focused on how future oil revenues should be divided between different states.