Former US President Donald Trump says his fraud case against him is "election interference" after winning a reduction in his $464million bond and a deadline extension.

Trump told reporters: "This is a case that could have been brought three and a half years ago, and now they're fighting over dates because they want to try and do it during the election.

"This is election interference, it's all it is, election interference. It's a disgrace and we will obviously be appealing. But this is a pure case of voter intimidation and election interference, and it shouldn't be allowed to happen."