Bruno Gollnisch made comments about the use of Nazi gas chambers and the number of Jews killed during World War II at a news conference in October 2004.
The EU assembly voted to remove his diplomatic immunity, saying the remarks were made in a personal capacity.
He is number two behind Jean-Marie Le Pen in the National Front Party.
Mr Gollnisch is due to face trial at a court in Lyon in May 2006 on a charge of contesting the existence of crimes against humanity.
In October 2004, Mr Gollnisch told a news conference he did not contest the "hundreds of thousands, the millions of deaths" during the Holocaust, but added: "As to the way those people died, a debate should take place."
He also said he did not deny the existence of deadly gas chambers, but that historians should debate this too.
His comments outraged Jewish and anti-racism groups, and he was suspended for five years from the Jean Moulin University in Lyon where he taught law and Japanese.