Political affairs correspondent Mickael Szames said eight party security officers knocked him to the ground and hit him repeatedly, shouting abuse and slurs, for taking pictures at a reception Saturday.
"They later took my cell phone and demanded I delete the pictures, which were of no journalistic value whatsoever. They confiscated my press card and my watch," Szames said in a live broadcast from Tours.
Szames was in Tours to report on the change in the National Front leadership from founder Jean-Marie Le Pen to his daughter, Marine.
Szames said he reported the assault to police immediately, but they told him they had little power within the walls of the meeting.
Szames filed assault charges against the security personnel, and France 24 has stopped direct coverage of the congress.
National Front communications director Alain Vizier said the party threatened to sue France 24 and another network, i-Tele, for reporting on the assault.