Brazil is blaming Venezuela for a mysterious oil spill on its beaches, and it's sending 5,000 troops to clean up the mess

• Oil has been washing up on beaches in northeastern Brazil since early in September.
• Brazil is blaming Venezuela, but the oil's origin is still unclear, and now Brasilia is sending in thousands of troops to help clean it up.
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Brazil's environment minister said Wednesday that the government will call on the Organization of American States to demand an answer from Venezuela over a mysterious oil spill affecting a large part of Brazil's northeastern coast.

In an official message broadcast on TV, the minister, Ricardo Salles, insisted that the oil is Venezuelan, a claim the Brazilian government has maintained for over a week, though it hasn't directly blamed Venezuela's government.

Hundreds of tons of oil have washed up on shore in many of Brazil's northeastern beaches, and its origins have not yet been fully explained.

Brazil's environmental agency, Ibama, began investigating the oil on September 2 and has said that an 1,860-mile swath of coastline in Brazil's Northeast region - some of the nicest beaches in the country - had been hit by the spill.

Beaches in the northeast, such as Praia do Futuro, in the state of Ceara, and Maragogi, in Alagoas state, are affected, as were beaches in the states of Rio Grande do Norte, Maranhao, Paraiba, Pernambuco, and Sergipe, according to Ibama. Animals have also been found dead or coated with oil.

Petrobras, as Brazil's state-run oil company is known, analyzed crude oil found on the beaches in late September, saying that "specific molecules" showed that it was neither produced nor sold by the company. In early October, Petrobras' CEO called the spill "something extraordinary."

Salles, the environmental minister, told lawmakers on October 9 that the crude was "very likely from Venezuela, citing a Petrobras report, and that "all indications" were the spill was caused by a foreign ship sailing near the coast.

Roughly a week later, Brazil said it had confirmed the oil's origins but not the reason for the spill.

"This oil is Venezuelan. Its DNA is Venezuelan. This is certain," Ibama President Eduardo Bim told a Senate hearing on October 17. "Does that mean that Venezuela is responsible? No, that is separate question."

Bim said there was no doubt the spill was caused by criminal activity, as it would have been reported otherwise. He said it probably happened during a ship-to-ship transfer, when oil is passed between two vessels at sea.

Brazil's navy has already begun asking oil tankers from several different countries for clarifications of their actions.

'Unprecedented in the world'

Venezuela has denied responsibility, and now, in addition to calling on the OAS to get an answer from Caracas, Brazil plans to send 5,000 troops to the most affected areas.

"This accident is unprecedented in the world," Vice President Hamilton Mourão said during the announcement Wednesday. Brazil's government has been criticized for a slow response, which Mourão rejected, saying 1,600 troops have spent weeks cleaning it up.

Petrobras said Monday it has collected 280 metric tons of oil and sand from northeastern beaches. Mourão said Wednesday that 600 metric tons of crude had been recovered.

Regardless of the culprit, this kind of spill will be more difficult to clean up. The crude doesn't float on the surface, only appearing when it hits a beach, so the usual methods to pick it up at sea have been ineffective.

Moreover, while the volume washing up on beaches remains relatively stable, it's unclear how much more there will be, a Petrobras source told Reuters.

"Until we know what actually happened, it will be difficult to predict when the leak will stop," the person said. "If a ship with a large oil load has sunk, the leak may still be happening."

(Reporting for Reuters by Marcelo Rochabrun; editing by Himani Sarkar)