Moody's Downgrades Ratings for Scandal-hit Petrobras

International ratings agency Moody's said Tuesday it had downgraded all ratings for scandal-plagued Brazilian oil giant Petrobras.

Until recently, Petrobras had been considered one of the best and most prestigious businesses in Brazil. But Moody's dropped its unsecured debt rating from Baa3 to Ba2.

"These rating actions reflect increasing concern about corruption investigations and liquidity pressures that might result from delays in delivering audited financial statements, as well as Moody's expectation that the company will be challenged to make meaningful reduction in its very high debt burden over the next several years," Moody's said in a statement.

It is the fourth time Moody's has downgraded Petrobras since October and it warned the oil giant's ratings remain on review for further downgrade. Some 48 percent of the company is controlled by the Brazilian state.

Petrobras is reeling from allegations of corruption on a massive scale with kickbacks and political payoffs costing Brazil's biggest company an estimated $3.8 billion.

Also on Tuesday, former president Luiz Inacio Lula da Silva visited oil workers at a union meeting and told them to stand up for Petrobras.

"We must punish those guilty of corruption but we mustn't throw Petrobras in the trash," Lula said.