Labour says the Government could have stopped a potential third credit downgrade from being predicted.
Standard & Poor's and Fitch downgraded New Zealand to AA on 30 September, mainly out of concern about the level of international debt.
The Prime Minister now says he can't rule out a credit downgrade by ratings agency Moody's.
Finance Minister Bill English says Moody's raised the same issues as other ratings agencies when he met their representatives.
But Labour's finance spokesperson David Cunliffe told Morning Report the Government should have tackled the underlying problems affecting the economy.
He said the downgrade will feed through to interest rates and affect exporters.
Listen to more from David Cunliffe