An oil spill was discovered off Brazil\'s coast near the country\'s Espirito Santo state, Brazil\'s Navy said on Thursday, the latest in a series of spills that have raised questions about the safety of a massive expansion of the country\'s oil production capacity. The Navy said it has sent a team to investigate and has no immediate estimate of the leak\'s size. Petrobras informed Ibama, Brazil\'s environmental protection agency, of the problem on Wednesday, said a press spokeswoman for the agency in Vitoria, Espirito Santo\'s capital. Spokespeople at Petrobras, the state-controlled oil company, declined to comment. Oil workers returning home after work offshore said there was an oil stain about 1 kilometer (0.6 mile) long on the ocean near the company\'s P-57 oil platform, the Folha de S. Paulo daily newspaper reported on Thursday. The P-57, a converted oil tanker, works in the Jubarte field about 85 kilometers (53 miles) off Brazil\'s coast. Jubarte produced 186,000 barrels of oil per day in February, or more than 8 percent of Brazil\'s total oil output of 2.1 million bpd, according to Brazil\'s oil regulator, the ANP. Jubarte is the fourth largest producing oil field in the country. When natural gas is added, production was equivalent to 198,000 barrels of oil per day (boepd). To tap its growing reserves, Petrobras plans to spend about $225 billion over five years to more than double output to about 6 million boepd in 2020 from 2.63 million barrels of oil and gas equivalent today. The vast majority of that oil will come from offshore fields near Rio de Janeiro and Sao Paulo. Recent spills, though, have cast a spotlight on Brazil\'s ambitious plans and its capacity to develop its giant, but technically challenging deepwater fields. Discoveries over the past five years rank among the largest anywhere in the last three decades and could allow Brazil to leapfrog the United States as the world\'s third-biggest oil producer. A spill in the Frade field south of Jubarte in November led to civil lawsuits seeking about $20 billion in damages and criminal charges against Chevron, which operates the field, as well as Transocean, its drilling contractor, and 17 of the two companies\' employees. Chevron and its partners in the field decided to shut down output in Frade after additional, unexplained leaks were found in field waters in March. Frade produced 64,000 barrels a day of oil in February, the ANP said. Chevron and Transocean deny any wrongdoing. Chevron owns 52 percent of Frade and Petrobras owns 30 percent. The rest is owned by a Japanese group led by Inpex and Sojitz Corp. The ANP said officials were not immediately available for comment. Petrobras preferred shares, the company\'s most-traded class of stock, fell 3.37 percent to 18.62 reais in Sao Paulo trading. The benchmark Bovespa index of the most-traded stocks on the Sao Paulo stock exchange fell 0.33 percent.