SAO PAULO- Brazilian police on Wednesday expanded the Car Wash corruption investigation to alleged kickbacks valued at $8 million on contracts for bunker fuel bought by state-run oil company Petroleo Brasileiro SA for its fleet of tankers.

A police statement said searches were carried out in Rio de Janeiro in the investigation, which targets unnamed Petrobras officials for transactions between 2009 and 2013 based on information obtained in plea bargain deals with defendants.

The head of the Car Wash prosecutors team based in Curitiba, Alessandro Oliveira, said the new investigation has detected initial estimated losses of $8 million in graft.

He said prosecutors were looking into transactions in Brazil and the port of Singapore.

Car Wash, or Lava Jato, began in 2014 with the arrest of a currency dealer and mushroomed into Brazl's biggest ever graft scandal mainly involving Petrobras contracts in which some 200 businessmen, officials and politicians have been convicted.

"Even though the Car Wash investigation uncovered a mega-corruption network, it is still steaming ahead and has a wide horizon of illegal practices to be investigated," Oliveira said in a video statement.

(Reporting by Ana Mano and Anthony Boadle; Editing by Steve Orlofsky) ((ana.mano@thomsonreuters.com; Tel: +55-11-5644-7704; Mob: +55-119-4470-4529; Reuters Messaging: ana.mano.thomsonreuters.com@reuters.net))