Mayor Bill de Blasio dismissed criticism from the Board of Elections' chief enforcement officer Monday.
In a confidential document that was leaked to the press, the officer accused de Blasio of "willful and flagrant" violations that warranted "criminal prosecution."
The leak happened amid a federal investigation into de Blasio's campaign finances.
"It's outrageous," de Blasio said about the leaked letter. He and his lawyer also maintained that the campaign did not violate any finance laws.