Prime Minister John Key says banks will have to pay their share of the losses from Solid Energy.
The state-owned coal company is in financial difficulty, with debts of $390 million.
Mr Key said commercial banks making loans to SOEs must realise there is no government guarantee.
In Solid Energy's case, he said, the banks won't be let off scot-free.
He said they will have to wear some of the loss, and can't expect the Government to fully bail them out.
Mr Key said the Government is continuing to work with Solid Energy and its bankers to restructure the company.