Petrobras has launched a program to buy back up to $2 billion of existing bonds in cash and the offering of new debt, as it seeks to refinance debt maturing before the end of the decade.

In a statement, Petrobras, which is the world's most indebted oil company, said seven different series of fixed- and floating-rate notes offered by the Petrobras Global Finance BV subsidiary will be targets of the repurchase program.

The bonds, which include notes maturing in Jan. 2019, March 2019, April 2019, Jan. 2020 and March 2020, have almost $10 billion outstanding worth of securities.