A Supreme Court judge has blasted Attorney-General Mark Dreyfus for a shock decision to stop funding the legal representation of convicted fraudster Adam Cranston in the lead-up to his sentencing.

In extraordinary scenes in the Sydney courtroom on Thursday morning, a representative for the attorney-general’s office told the court it had been decided on Monday to cease Commonwealth funding of Mr Cranston’s defence, despite having done so for two years and during his nine-month trial.