A Portuguese bank salvaged from the collapse of a major lender has reported losses of 981 million euros ($1 billion) in 2015, casting a cloud over the government's attempts to sell it.

Novo Banco, a so-called good bank that emerged from the surprise 2014 bankruptcy of Banco Espirito Santo, said Wednesday legacy debts soured its performance.

The bank last year controversially transferred some 2 billion euros of debt back to Banco Espirito Santo, which is being wound up, to help its balance sheet.

Novo Banco received 4.9 billion euros to keep it afloat. The government hopes to recoup that by selling the bank, but a first attempt last September failed when the Bank of Portugal said the offers were too low. It is expected to try again in coming months.