Earlier this week, Fitch downgraded its outlook for the Netherlands as a whole from stable to negative, saying falling house prices are not good for consumer confidence and are depressing spending power. The country retained its AAA status.
All three banks are either state owned or have had state support. BNG is the state-run local authorities bank.
In a statement, Fitch said the nationalisation of financial services group SNS Reaal last week shows the Dutch banking sector is not yet out of trouble.