Brazilian state-run oil company Petrobras said it has sold $2.5 billion in 100-year bonds, as its cost of borrowing surged in the wake of a giant corruption scandal and concern about its soaring debt, one of the world’s largest, rose.

Petroleo Brasileiro, as the company is formally known, sold the 6.85 per cent bonds due in June 2115 at 81.07 per cent of face value to yield 8.45 per cent.

Because of the discount, Petrobras raised about $2.03 billion in the sale.

While the sale shows that investors are still willing to loan money to the company after a price-fixing, bribery and political kick-back scandal led to about $17 billion in write-downs, investors are demanding higher returns from the Rio de Janeiro-based company despite low international interest rates.

Petrobras sold $1.8 billion of 5.625 per cent 30-year bonds in May 2013 to yield 7.3 per cent; it was borrowing similar amounts in dollars for less than 4 per cent as recently as 2012. Deutsche Bank and JP Morgan managed the sale.

Petrobras has turned increasingly to China’s banks for financing and signed $7 billion-worth in loans during the visit to Brasilia by Chinese Premier Li Keqiang last month. The company said it finalized a 5-year export financing loan of 3 billion reais ($945.3 million) for its unit Petrobras Distribuidora SA.