Police in Brazil have identified a Greek-controlled tanker as the source of a huge oil spill off the country's northeastern coast in September.

Federal authorities in the city of Natal have issued two search-and-seizure warrants targeting the Rio de Janeiro offices of the unidentified Greek owner of the vessel, Upstream's sister shipping news source TradeWinds reported.

News that a vessel has been identified comes as crude continues to wash up on 2500 kilometres of Brazil's coastline after a leak thought to have taken place 700 kilometres out at sea between July 28 and 29.

Some 250 beaches have been impacted by the spill.

Reuters reported that Brazil has so far collected 2000 tonnes of sludge.

The Brazilian Navy believes the oil came from a ship-to-ship transfer that went wrong. Another theory is that a vessel released crude to increase its stability.

Until Friday's police announcement, 10 tankers had been on a list of possible culprits, down from 1500 ships that were in the area at the time.

Read the full story in TradeWinds.