Confirming a report in Le Monde newspaper, FN treasurer Wallerand de Saint-Just said the charges brought by French prosecutors on November 30 were the "natural follow-on" from the charges laid against party leader Marine Le Pen in June.
The FN is accused of illegally claiming millions of euros from the European Parliament in funds earmarked for parliamentary assistants, to pay France-based staff instead.
In a statement Tuesday the party said it would prove "that it did not embezzle a penny".
Le Pen, who was beaten by Emmanuel Macron in May's presidential election run-off, has also denied the charges.
She is one of 17 FN lawmakers -- along with her estranged father Jean-Marie Le Pen and her partner, FN vice-president Louis Aliot -- being investigated over salaries paid to around 40 parliamentary assistants.
The affair first made headlines during the election but took a back seat to the scandal ensnaring Le Pen's conservative rival Francois Fillon.
Fillon, the one-time favourite, crashed out of the election at the first round after it emerged that his wife was paid nearly 700,000 euros for a suspected fake job as a French parliamentary assistant.
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